Added a pr validator

.github/workflows/validate.yml

@@ -0,0 +1,21 @@
+name: Pull Request Validation
+
+on:
+  pull_request:
+    branches: [main]
+
+jobs:
+  validate:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python
+        uses: actions/setup-python@v2
+        with:
+          python-version: "3.x"
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install primal-page
+      - name: Run primal-page validate
+        run: primal-page validate directory ./primerschemes