removed old workflow

.github/workflows/ci.yml

@@ -1,25 +0,0 @@
-name: CI
-
-on:
-  push:
-    branches: [master]
-  pull_request:
-    branches: [master]
-
-jobs:
-  ci:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: shivammathur/setup-php@v2
-        with:
-          php-version: '8.3'
-          coverage: none
-      - name: Install dependencies
-        run: composer install --prefer-dist --no-progress
-      - name: PHPStan
-        run: composer phpstan
-      - name: Code style check
-        run: composer cs-check
-      - name: Tests
-        run: composer test