Add PHP 8.1 back to CI matrix

composer.lock is gitignored so CI resolves fresh — PHP 8.1 gets
Pest v2, PHP 8.2+ gets Pest v3. Tests the full declared range.

Author: devlob

.github/workflows/tests.yml

@@ -11,7 +11,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php: ['8.2', '8.3', '8.4']
+        php: ['8.1', '8.2', '8.3', '8.4']
 
     name: PHP ${{ matrix.php }}