I am trying to set up Github Actions for a C++ code base with Qt5 dependency and CMake as a build system.

Being novice with Github Actions, I started with the cmake-multi-platform template, where I inserted the following step before cmake is called :

    - name: Install Qt
      uses: jurplel/install-qt-action@v4
      with:
        version: '5.15.2'
        dir: '${{ github.workspace }}/extern/'
        install-deps: 'true'
        archives: 'qtbase'
        cache: 'true'
        cache-key-prefix: 'install-qt-action'

I also added an env key to the configuration step:

    - name: Configure CMake
      env:
        CMAKE_PREFIX_PATH: ${{env.Qt5_DIR}}
      run: >
        cmake -B ${{ steps.strings.outputs.build-output-dir }}
        -DCMAKE_CXX_COMPILER=${{ matrix.cpp_compiler }}
        -DCMAKE_C_COMPILER=${{ matrix.c_compiler }}
        -DCMAKE_BUILD_TYPE=${{ matrix.build_type }}
        -S ${{ github.workspace }}

This was eventually enough to have CMake configuration run without errors.

The compilation step fails with the following messages

/usr/bin/ld: warning: libicui18n.so.56, needed by /home/runner/work/pptranspog/pptranspog/extern/Qt/5.15.2/gcc_64/lib/libQt5Core.so.5.15.2, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: libicuuc.so.56, needed by /home/runner/work/pptranspog/pptranspog/extern/Qt/5.15.2/gcc_64/lib/libQt5Core.so.5.15.2, not found (try using -rpath or -rpath-link)
/usr/bin/ld: warning: libicudata.so.56, needed by /home/runner/work/pptranspog/pptranspog/extern/Qt/5.15.2/gcc_64/lib/libQt5Core.so.5.15.2, not found (try using -rpath or -rpath-link)
/usr/bin/ld: /home/runner/work/pptranspog/pptranspog/extern/Qt/5.15.2/gcc_64/lib/libQt5Core.so.5.15.2: undefined reference to `ucol_open_56'
...

followed by a string of undefined references to ICU functions called by the Qt5 library.

I assumed that setting install-deps to true when installing Qt should have installed all its dependencies. That is apparently not the case.

What would be the recommended solution in this situation?