fix: update CI workflow for PHP 8.4

- Update actions/checkout to v4
- Replace ramsey/composer-install with direct composer install
- Remove stale feature/saloon-v2 branch trigger

Author: tance77

.github/workflows/phpstan.yml

@@ -4,7 +4,6 @@ on:
   push:
     branches:
       - 'main'
-      - 'feature/saloon-v2'
   pull_request:
     branches:
       - '*'
@@ -14,16 +13,16 @@ jobs:
     name: phpstan
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Setup PHP
         uses: shivammathur/setup-php@v2
         with:
-          php-version: '8.3'
+          php-version: '8.4'
           coverage: none
 
       - name: Install composer dependencies
-        uses: ramsey/composer-install@v2
+        run: composer install --no-interaction --prefer-dist
 
       - name: Run PHPStan
-        run: ./vendor/bin/phpstan analyse --error-format=github
+        run: ./vendor/bin/phpstan analyse --error-format=github