Update linting to all supported php versions

Signed-off-by: Joas Schilling <coding@schilljs.com>

.github/workflows/lint.yml

@@ -13,14 +13,14 @@ jobs:
 
     strategy:
       matrix:
-        php-versions: ['7.2', '7.3', '7.4']
+        php-versions: ['7.2', '7.3', '7.4', '8.0']
 
     name: php${{ matrix.php-versions }}
     steps:
       - uses: actions/checkout@v2
 
       - name: Set up php ${{ matrix.php-versions }}
-        uses: shivammathur/setup-php@v1
+        uses: shivammathur/setup-php@v2
         with:
           php-version: ${{ matrix.php-versions }}
           coverage: none
@@ -29,18 +29,26 @@ jobs:
         run: composer run lint || ( echo 'Please run `composer run lint` and fix your code' && exit 1 )
 
   php-cs-fixer:
-    name: php-cs check
     runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php-versions: ['7.4']
+
+    name: cs php${{ matrix.php-versions }}
     steps:
       - name: Checkout
-        uses: actions/checkout@master
+        uses: actions/checkout@v2
+
       - name: Set up php
-        uses: shivammathur/setup-php@master
+        uses: shivammathur/setup-php@v2
         with:
-          php-version: 7.4
+          php-version: ${{ matrix.php-versions }}
           coverage: none
+
       - name: Install dependencies
         run: composer i
+
       - name: Run coding standards check
         run: composer run cs:check || ( echo 'Please run `composer run cs:fix` to format your code' && exit 1 )
 
@@ -48,9 +56,11 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@master
+        uses: actions/checkout@v2
+
       - name: Download schema
         run: wget https://apps.nextcloud.com/schema/apps/info.xsd
+
       - name: Lint info.xml
         uses: ChristophWurst/xmllint-action@v1
         with: