Add workflow to update node_modules on master

.github/workflows/master.yml

@@ -0,0 +1,42 @@
+name: master
+
+on:
+  push:
+    branches:
+      - 'master'
+    paths:
+      - 'package.*'
+      - '.github/workflows/master.yml'
+
+jobs:
+  prune:
+    runs-on: ubuntu-latest
+    steps:
+      -
+        name: Checkout
+        uses: actions/checkout@v1
+      -
+        # https://github.com/actions/checkout/issues/6
+        name: Fix detached HEAD
+        run: git checkout ${GITHUB_REF#refs/heads/}
+      -
+        name: Prune prod
+        run: |
+          rm -rf node_modules
+          npm install --production
+      -
+        name: Set up Git
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          git config user.name "${GITHUB_ACTOR}"
+          git config user.email "${GITHUB_ACTOR}@users.noreply.github.com"
+          git remote set-url origin https://x-access-token:${GITHUB_TOKEN}@github.com/${GITHUB_REPOSITORY}.git
+      -
+        name: Commit and push changes
+        run: |
+          git add --all
+          git status --short -uno
+          git commit -m 'Update node_modules'
+          git show --stat-count=10 HEAD
+          git push