refactor: simplify lint job with parallel feature

Signed-off-by: Bart Jaskulski <bjaskulski@protonmail.com>

includes/tests/lint.yml

-.lint: &lint-tmpl
+lint:
+  image: gitlab.wpdesk.dev:5050/wpdesk/docker-tests/php-box:${PHP_IMAGE}
   needs:
     - prepare prefixed vendor
   stage: tests
@@ -10,17 +11,12 @@
   script:
     - parallel-lint . --gitlab > lint-codequality.json || true
     - parallel-lint . --no-progress
+  parallel:
+    matrix:
+      - PHP_IMAGE: ["8.3.2", "7.4.1"]
   artifacts:
     paths:
       - lint-codequality.json
     expire_in: 1 week
     reports:
       codequality: lint-codequality.json
-
-lint:8.3:
-  extends: .lint
-  image: gitlab.wpdesk.dev:5050/wpdesk/docker-tests/php-box:8.3.2
-
-lint:7.4:
-  extends: .lint
-  image: gitlab.wpdesk.dev:5050/wpdesk/docker-tests/php-box:7.4.1