Add PHP 8.4 to CI, and cleanup CI config

Author: samwilson

.github/workflows/ci.yml

@@ -13,24 +13,23 @@ jobs:
 
     strategy:
       matrix:
-        php: [ '7.4', '8.0', '8.1', '8.2', '8.3' ]
+        php: [ '7.4', '8.0', '8.1', '8.2', '8.3', '8.4' ]
 
     runs-on: ubuntu-latest
 
     name: PHP ${{ matrix.php }}
 
     steps:
     - name: Checkout
-      uses: actions/checkout@v1
+      uses: actions/checkout@v5
 
     - name: Set up PHP
       uses: shivammathur/setup-php@v2
       with:
         php-version: ${{matrix.php}}
 
     - name: Install
-      run: |
-        composer install
+      run: composer install
 
     - name: Test
       run: composer test