Remove PHP 8.1 and 8.2 from CI pipeline testing matrix

Author: Sergey Lavrienya

.github/workflows/phpunit.yml

@@ -13,6 +13,6 @@ jobs:
             os: >-
                 ['ubuntu-latest']
             php: >-
-                ['8.1', '8.2', '8.3', '8.4']
+                ['8.3', '8.4']
             stability: >-
                 ['prefer-lowest', 'prefer-stable']