update workflow to use clang instead of gcc

Author: phlptp

.github/workflows/packaging.yml

@@ -75,8 +75,16 @@ jobs:
   install-module:
     name: Install Module Tests
     runs-on: ubuntu-latest
-    container: gcc:15
     steps:
+      - name: Set up Clang
+        uses: egor-tensin/setup-clang@v2
+        with:
+          version: 20
+          platform: x64
+      - name: Install specific libc++ version
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y libc++-20-dev libc++abi-20-dev lld-20
       - uses: actions/checkout@v6
         with:
           submodules: true
@@ -93,8 +101,9 @@ jobs:
             -DUNITS_ENABLE_TESTS=ON \
             -DUNITS_INSTALL_PACKAGE_TESTS=ON \
             -DUNITS_BUILD_SHARED_LIBRARY=ON \
+            -DCMAKE_CXX_COMPILER=clang++ -DCMAKE_LINKER_TYPE=LLD -DCMAKE_CXX_FLAGS=-stdlib=libc++
             -DUNITS_BUILD_CXX_MODULE=ON \
-            -DCMAKE_CXX_STANDARD=20 \
+            -DCMAKE_CXX_STANDARD=23 \
             -DCMAKE_INSTALL_PREFIX=/home/runner/work/install
 
       - name: Build