Add workflow to check and update requirements files

This workflow runs an action on a pull request into main that
compiles the requirements files; opens a pull request if changes
are detected; and then exits successfully if no changes are detected
or unsuccessfully if changes are detected.

.github/workflows/pip-compile.yml

@@ -0,0 +1,29 @@
+name: Update pip-tools requirements files
+on:
+  pull_request:
+    branches: [ "main" ]
+
+
+jobs:
+  update-requirements-files:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout Code Repository
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+
+      - name: Set up Python 3.9
+        uses: actions/setup-python@v5
+        with:
+          python-version: 3.9
+
+      - name: Update requirements files
+        uses: UW-GAC/pip-tools-actions/update-requirements-files@v1
+        with:
+          requirements_files:  |-
+            requirements/requirements.in
+            requirements/test-requirements.in
+            requirements/dev-requirements.in
+          pr-branch-suffix: "${{ github.event.number}}"