Update build-deps to use new dependency string parsing

src/dds/deps.cpp

 #include <dds/util/string.hpp>
 
 #include <json5/parse_data.hpp>
-#include <semester/decomp.hpp>
+#include <semester/walk.hpp>
 
 #include <spdlog/fmt/fmt.h>
 
     auto data    = json5::parse_data(content);
 
     dependency_manifest depman;
-    using namespace semester::decompose_ops;
-    auto res = semester::decompose(
+    using namespace semester::walk_ops;
+    auto res = walk.try_walk(  //
         data,
-        try_seq{
-            require_type<json5::data::mapping_type>{
-                "The root of a dependency manifest must be an object (mapping)"},
-            mapping{
-                if_key{"$schema", just_accept},
-                if_key{"depends",
-                       require_type<json5::data::mapping_type>{
-                           "`depends` must be a mapping between package names and version ranges"},
-                       mapping{[&](auto pkg_name, const json5::data& range_str_) {
-                           if (!range_str_.is_string()) {
-                               throw_user_error<errc::invalid_pkg_manifest>(
-                                   "Issue in dependency manifest: Dependency for '{}' must be a "
-                                   "range string",
-                                   pkg_name);
-                           }
-                           try {
-                               auto rng = semver::range::parse_restricted(range_str_.as_string());
-                               dependency dep{std::string(pkg_name), {rng.low(), rng.high()}};
-                               depman.dependencies.push_back(std::move(dep));
-                           } catch (const semver::invalid_range&) {
-                               throw_user_error<errc::invalid_version_range_string>(
-                                   "Invalid version range string '{}' in dependency declaration "
-                                   "for '{}'",
-                                   range_str_.as_string(),
-                                   pkg_name);
-                           }
-                           return semester::dc_accept;
-                       }}},
-                [&](auto key, auto&&) {
-                    return semester::dc_reject_t{
-                        fmt::format("Unknown key `{}` in dependency manifest", key)};
-                }},
+        require_type<json5::data::mapping_type>{
+            "The root of a dependency manifest must be a JSON object"},
+        mapping{
+            required_key{
+                "depends",
+                "A 'depends' key is required",
+                require_type<json5::data::array_type>{"'depends' must be an array of strings"},
+                for_each{
+                    require_type<std::string>{"Each dependency should be a string"},
+                    put_into(std::back_inserter(depman.dependencies),
+                             [](const std::string& str) {
+                                 return dependency::parse_depends_string(str);
+                             }),
+                },
+            },
         });
-    auto rej = std::get_if<semester::dc_reject_t>(&res);
-    if (rej) {
-        throw_user_error<errc::invalid_pkg_manifest>(rej->message);
-    }
+
+    res.throw_if_rejected<user_error<errc::invalid_pkg_manifest>>();
 
     return depman;
 }

tests/deps/build-deps/project/deps.json5

 {
-    depends: {
-        'neo-sqlite3': '+0.3.0',
-    },
+    depends: [
+        'neo-fun+0.3.0'
+    ],
 }

tests/deps/build-deps/test_build_deps.py

     assert not dds.deps_build_dir.is_dir()
     dds.catalog_import(dds.source_root / 'catalog.json')
     dds.build_deps(['-d', 'deps.json5'])
-    assert (dds.deps_build_dir / 'neo-sqlite3@0.3.0').is_dir()
+    assert (dds.deps_build_dir / 'neo-fun@0.3.0').is_dir()
     assert (dds.scratch_dir / 'INDEX.lmi').is_file()
-    assert (dds.deps_build_dir / '_libman/neo-sqlite3.lmp').is_file()
-    assert (dds.deps_build_dir / '_libman/neo/sqlite3.lml').is_file()
+    assert (dds.deps_build_dir / '_libman/neo-fun.lmp').is_file()
+    assert (dds.deps_build_dir / '_libman/neo/fun.lml').is_file()
 
 
 def test_build_deps_from_cmd(dds: DDS):
     assert not dds.deps_build_dir.is_dir()
     dds.catalog_import(dds.source_root / 'catalog.json')
-    dds.build_deps(['neo-sqlite3=0.3.0'])
-    assert (dds.deps_build_dir / 'neo-sqlite3@0.3.0').is_dir()
+    dds.build_deps(['neo-fun=0.3.0'])
+    assert (dds.deps_build_dir / 'neo-fun@0.3.0').is_dir()
     assert (dds.scratch_dir / 'INDEX.lmi').is_file()
-    assert (dds.deps_build_dir / '_libman/neo-sqlite3.lmp').is_file()
-    assert (dds.deps_build_dir / '_libman/neo/sqlite3.lml').is_file()
+    assert (dds.deps_build_dir / '_libman/neo-fun.lmp').is_file()
+    assert (dds.deps_build_dir / '_libman/neo/fun.lml').is_file()
 
 
 def test_multiple_deps(dds: DDS):
     assert not dds.deps_build_dir.is_dir()
     dds.catalog_import(dds.source_root / 'catalog.json')
-    dds.build_deps(['neo-sqlite3^0.2.0', 'neo-sqlite3~0.3.0'])
-    assert (dds.deps_build_dir / 'neo-sqlite3@0.3.0').is_dir()
+    dds.build_deps(['neo-fun^0.2.0', 'neo-fun~0.3.0'])
+    assert (dds.deps_build_dir / 'neo-fun@0.3.0').is_dir()
     assert (dds.scratch_dir / 'INDEX.lmi').is_file()
-    assert (dds.deps_build_dir / '_libman/neo-sqlite3.lmp').is_file()
-    assert (dds.deps_build_dir / '_libman/neo/sqlite3.lml').is_file()
+    assert (dds.deps_build_dir / '_libman/neo-fun.lmp').is_file()
+    assert (dds.deps_build_dir / '_libman/neo/fun.lml').is_file()