`catch-runner` isn't even a thing

src/dds/build.cpp

 
     if (test_driver == test_lib::catch_) {
         // Don't generate a test library helper
+        return;
     }
 
     std::string fname;
     if (test_driver == test_lib::catch_main) {
         fname      = "catch-main.cpp";
         definition = "CATCH_CONFIG_MAIN";
-    } else if (test_driver == test_lib::catch_runner) {
-        fname      = "catch-runner.cpp";
-        definition = "CATCH_CONFIG_RUNNER";
     } else {
         assert(false && "Impossible: Invalid `test_driver` for catch library");
         std::terminate();
                          const package_manifest& man,
                          build_env_ref           env) {
     auto& test_driver = *man.test_driver;
-    if (test_driver == test_lib::catch_ || test_driver == test_lib::catch_main
-        || test_driver == test_lib::catch_runner) {
+    if (test_driver == test_lib::catch_ || test_driver == test_lib::catch_main) {
         prepare_catch2_driver(lib_params, test_driver, params, env);
     } else {
         assert(false && "Unreachable");

src/dds/package_manifest.cpp

         auto& test_driver_str = *opt_test_driver;
         if (test_driver_str == "Catch-Main") {
             ret.test_driver = test_lib::catch_main;
-        } else if (test_driver_str == "Catch-Runner") {
-            ret.test_driver = test_lib::catch_runner;
         } else if (test_driver_str == "Catch") {
             ret.test_driver = test_lib::catch_;
         } else {

src/dds/package_manifest.hpp

 enum class test_lib {
     catch_,
     catch_main,
-    catch_runner,
 };
 
 struct package_manifest {