chore: Switch to github setup-php v2

Author: Stephan Wentz

.github/workflows/tests.yaml

@@ -16,7 +16,7 @@ jobs:
     name: Tests on PHP ${{ matrix.php-versions }}
     steps:
     - uses: actions/checkout@master
-    - uses: shivammathur/setup-php@v1
+    - uses: shivammathur/setup-php@v2
       with:
         php-version: ${{ matrix.php-versions }}
         coverage: none
@@ -39,7 +39,7 @@ jobs:
     name: Tests with lowest dependencies
     steps:
       - uses: actions/checkout@master
-      - uses: shivammathur/setup-php@v1
+      - uses: shivammathur/setup-php@v2
         with:
           php-version: 7.3
           coverage: none