minor #2852 [CI] Reduce number of PHPStan jobs (Kocal)

This PR was merged into the 2.x branch.

Discussion
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[CI] Reduce number of PHPStan jobs

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Docs?         | no <!-- required for new features -->
| Issues        | Fix #... <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT

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After some reflexions, I don't think there is a need to run PHPStan over all supported PHP versions, only the lowest one we support (8.1) and highest one (8.4) is enough.

Playing with dependency versions, stability, and Symfony versions still make sense

Commits
-------

606d7f7 [CI] Reduce number of PHPStan jobs

Author: Kocal

.github/workflows/code-quality.yaml

@@ -46,17 +46,18 @@ jobs:
         strategy:
             fail-fast: false
             matrix:
-                php-version: [ '8.1', '8.2', '8.3', '8.4']
+                php-version: ['8.1']
                 dependency-version: ['']
                 symfony-version: ['']
                 minimum-stability: ['stable']
                 include:
+                    # dev packages (probably not needed to have multiple such jobs)
+                    - minimum-stability: 'dev'
+                      php-version: 8.4
                     # lowest deps
-                    -   php-version: '8.1'
-                        dependency-version: 'lowest'
+                    - dependency-version: 'lowest'
                     # LTS version of Symfony
-                    -   php-version: '8.1'
-                        symfony-version: '6.4.*'
+                    - symfony-version: '6.4.*'
         steps:
             -   name: Checkout
                 uses: actions/checkout@v4
@@ -78,7 +79,7 @@ jobs:
             -   name: Setup PHP
                 uses: shivammathur/setup-php@v2
                 with:
-                    php-version: ${{ matrix.php-version }}
+                    php-version: 8.1
                     tools: flex
 
             - name: Install root dependencies