Upgrade cache action

Author: frankdejonge

.github/workflows/tests.yml

@@ -37,7 +37,7 @@ jobs:
         id: composer-cache
         run: |
           echo "::set-output name=dir::$(composer config cache-files-dir)"
-      - uses: actions/cache@v2
+      - uses: actions/cache@v3
         with:
           path: ${{ steps.composer-cache.outputs.dir }}
           key: ${{ runner.os }}-composer-${{ matrix.stability }}-${{ hashFiles('**/composer.lock') }}