Add gitlab action for wdl validation

.github/workflows/wdl_linter.yml

@@ -0,0 +1,28 @@
+name: MiniWDL linter CI
+
+on:
+  pull_request:
+    branches: master
+
+jobs:
+  run-miniwdl:
+    runs-on: ubuntu-latest
+
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v2
+
+    - name: Set up Python
+      uses: actions/setup-python@v2
+      with:
+        python-version: '3.8' # specify the Python version you need
+
+    - name: Install MiniWDL
+      run: |
+        python -m pip install --upgrade pip
+        pip install miniwdl
+
+    - name: Run MiniWDL
+      run: |
+        # Add the commands to run your MiniWDL workflow
+        miniwdl check --suppress UnknownRuntimeKey rqcfilter.wdl