GH Actions: update PHP ini configuration

Add `display_startup_errors=On` as per the current recommendation from PHPUnit.

Ref: sebastianbergmann/phpunit-documentation-english@b3b159c

Author: jrfnl

.github/workflows/release.yml

@@ -28,7 +28,7 @@ jobs:
           php-version: 8.0
           extensions: exif, phar, openssl
           coverage: none
-          ini-values: phar.readonly=Off, error_reporting=-1, display_errors=On, zend.assertions=1
+          ini-values: phar.readonly=Off, error_reporting=-1, display_errors=On, display_startup_errors=On, zend.assertions=1
 
       - name: Install Box
         run: composer global require humbug/box

.github/workflows/tests.yml

@@ -30,7 +30,7 @@ jobs:
       with:
         php-version: ${{ matrix.php-versions }}
         extensions: mbstring
-        ini-values: zend.assertions=1, error_reporting=-1, display_errors=On, log_errors_max_len=0
+        ini-values: zend.assertions=1, error_reporting=-1, display_errors=On, display_startup_errors=On, log_errors_max_len=0
         coverage: none
 
     # Install dependencies and handle caching in one go.