Remove deprecated action

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

.github/workflows/app-code-check.yml

@@ -1,55 +0,0 @@
-name: PHP AppCode Check
-
-on:
-  pull_request:
-  push:
-    branches:
-      - master
-      - stable*
-
-env:
-  APP_NAME: registration
-
-jobs:
-  unit-tests:
-    runs-on: ubuntu-latest
-
-    strategy:
-      matrix:
-        php-versions: ['7.4']
-        server-versions: ['stable20', 'stable21', 'master']
-
-    name: AppCode check php${{ matrix.php-versions }}-${{ matrix.server-versions }}
-    steps:
-      - name: Checkout server
-        uses: actions/checkout@v2
-        with:
-          repository: nextcloud/server
-          ref: ${{ matrix.server-versions }}
-
-      - name: Checkout submodules
-        shell: bash
-        run: |
-          auth_header="$(git config --local --get http.https://github.com/.extraheader)"
-          git submodule sync --recursive
-          git -c "http.extraheader=$auth_header" -c protocol.version=2 submodule update --init --force --recursive --depth=1
-
-      - name: Checkout app
-        uses: actions/checkout@v2
-        with:
-          path: apps/${{ env.APP_NAME }}
-
-      - name: Set up php ${{ matrix.php-versions }}
-        uses: shivammathur/setup-php@v2
-        with:
-          php-version: ${{ matrix.php-versions }}
-          tools: phpunit
-          extensions: mbstring, iconv, fileinfo, intl, sqlite, pdo_sqlite
-
-      - name: Checkout app
-        uses: actions/checkout@v2
-        with:
-          path: apps/${{ env.APP_NAME }}
-
-      - name: App code check
-        run: php occ app:check-code ${{ env.APP_NAME }}