GH Actions: set error reporting to E_ALL

The default setting for `error_reporting` used by the SetupPHP action is `error_reporting=E_ALL & ~E_DEPRECATED & ~E_STRICT` and `display_errors` is set to `Off`.

For the purposes of CI, I'd recommend running with `E_ALL` and `display_errors=On` to ensure **all** PHP notices are shown.

Author: jrfnl

.github/workflows/continuous-integration.yml

@@ -22,7 +22,7 @@ jobs:
         with:
           php-version: "7.4"
           coverage: "none"
-          ini-values: "memory_limit=-1"
+          ini-values: "memory_limit=-1, zend.assertions=1, error_reporting=-1, display_errors=On"
           tools: "composer:v2"
       - uses: "ramsey/composer-install@v1"
       - name: "Lint the PHP source code"
@@ -70,7 +70,7 @@ jobs:
         with:
           php-version: "${{ matrix.php-version }}"
           coverage: "pcov"
-          ini-values: "memory_limit=-1"
+          ini-values: "memory_limit=-1, zend.assertions=1, error_reporting=-1, display_errors=On"
           tools: "composer:v2"
       - name: "Prepare for tests"
         run: "mkdir -p build/logs"