Install python, pip and conan for CI (#156).

conanfile.txt

@@ -1,6 +1,6 @@
 [requires]
 Catch2/2.8.0@catchorg/stable
-trompeloeil/v34@rollbear/stable 
+trompeloeil/v34@rollbear/stable
 
 [generators]
 cmake_find_package

script/ci_build.sh

@@ -2,12 +2,18 @@
 
 set -ex
 
+# Conan
+apt-get install -y python3-pip
+pip3 install conan
+
+
 if [[ "${CXX}" == clang* ]]
 then
     export CXXFLAGS="-stdlib=libc++"
 fi
 
 mkdir build && cd build
+conan install --build missing ..
 
 cmake ..
 make