git: use ccache (#253)

.github/workflows/tests.yml

@@ -28,6 +28,7 @@ jobs:
         sudo apt update
         sudo apt install -y       \
             build-essential       \
+            ccache                \
             gcc-12                \
             g++-12                \
             lld                   \
@@ -41,12 +42,21 @@ jobs:
         
         sudo pip install jsonschema
 
+    - name: 📜 Setup ccache
+      uses: hendrikmuhs/ccache-action@v1
+      with:
+        key: ${{ runner.os }}-ccache-${{ github.run_id }}
+        restore-keys: ${{ runner.os }}-ccache
+        max-size: 1G
+
     - name: 🛠️ Build
       run: |
         cd tests
         mkdir -p build
         cd build
         CC=gcc-12 CXX=g++-12 cmake                        \
+          -DCMAKE_C_COMPILER_LAUNCHER=ccache              \
+          -DCMAKE_CXX_COMPILER_LAUNCHER=ccache            \
           -DCMAKE_C_FLAGS="-fuse-ld=lld --coverage"       \
           -DCMAKE_CXX_FLAGS="-fuse-ld=lld --coverage"     \
           -DLIBPL_ENABLE_TESTS=OFF                        \