CI: Do not save the ccache for PRs

Resolves #14155

Author: TimWolla

.github/workflows/push.yml

@@ -72,6 +72,7 @@ jobs:
           # job id, not the job name)
           key: "LINUX_X64_${{ matrix.debug && 'DEBUG' || 'RELEASE' }}_${{ matrix.zts && 'ZTS' || 'NTS' }}-${{hashFiles('main/php_version.h')}}"
           append-timestamp: false
+          save: ${{ github.event_name != 'pull_request' }}
       - name: ./configure
         uses: ./.github/actions/configure-x64
         with: