Add psalm workflow

Signed-off-by: Côme Chilliet <[email protected]>

.github/workflows/psalm.yml

@@ -0,0 +1,36 @@
+name: Static analysis
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+      - stable*
+
+jobs:
+  static-psalm-analysis:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        ocp-version: [ 'dev-master' ]
+
+    name: Nextcloud ${{ matrix.ocp-version }}
+    steps:
+      - name: Checkout
+        uses: actions/checkout@master
+
+      - name: Set up php
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: 7.4
+          coverage: none
+
+      - name: Install dependencies
+        run: composer i
+
+      - name: Install dependencies
+        run: composer require --dev christophwurst/nextcloud:${{ matrix.ocp-version }}
+
+      - name: Run coding standards check
+        run: composer run psalm