Fix clang-tidy config file path

It seems that using github.workspace doesn't work as intended, but just using a relative path from the top level directory seems to do the job.

.github/workflows/clang-tidy.yml

@@ -13,7 +13,7 @@ jobs:
       with:
         apt_packages: g++,libqt5opengl5-dev,libqt5svg5-dev,libglvnd-dev,libeigen3-dev,zlib1g-dev,libfftw3-dev,ninja-build
         cmake_command: cmake . -DCMAKE_EXPORT_COMPILE_COMMANDS=on
-        config_file: ${{ github.workspace }}/.clang-tidy
+        config_file: .clang-tidy
 
     - uses: ZedThree/clang-tidy-review/[email protected]
       id: upload-review