Fix timestamp generation, fix ccache cache path

CCache default path has changed to ~/.cache/ccache

Author: mariadb-TeemuOllakka

.github/workflows/build.yml

@@ -104,13 +104,13 @@ jobs:
       id: ccache_cache_timestamp
       shell: cmake -P {0}
       run: |
-        string(TIMESTAMP current_date "%Y-%m-%d-%H;%M;%S" UTC)
-        message("::set-output name=timestamp::${current_date}")
+        echo "sha=${{ github.event.pull_request.head.sha }}" >> $GITHUB_OUTPUT
+        echo "timestamp=$(git show -s --format=%ct ${{ github.event.pull_request.head.sha }})"
 
     - name: Configure ccache
       uses: actions/cache@v4
       with:
-        path: ~/.ccache
+        path: ~/.cache/ccache
         key: ${{ matrix.config.os }}-${{ matrix.config.CC }}-${{ matrix.config.version }}-${{ matrix.config.type }}-ccache-${{ steps.ccache_cache_timestamp.outputs.timestamp }}
         restore-keys: ${{ matrix.config.os }}-${{ matrix.config.CC }}-${{ matrix.config.version }}-${{ matrix.config.type }}-ccache-