CI: automate updating of mach-examples

Signed-off-by: Stephen Gutekanst <stephen@hexops.com>

.github/workflows/update_examples.yml

@@ -0,0 +1,33 @@
+name: Update examples
+on:
+  workflow_run:
+    workflows: ["CI"]
+    types:
+      - completed
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+jobs:
+  publish:
+    if: ${{ github.event.workflow_run.conclusion == 'success' }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v2
+      - name: Checkout hexops/mach-examples repo
+        uses: actions/checkout@v2
+        with:
+          repository: hexops/mach-examples
+          token: ${{ secrets.HEXOPS_MACH_GPU_DAWN_PUSH }}
+      - name: 'mach-examples: update mach submodule'
+        run: |
+          cd libs/mach
+          git pull
+          cd ../../
+      - name: 'gpu/dawn: use latest binary release'
+        run: |
+          git config user.name 'Release automation'
+          git config user.email 'stephen@hexops.com'
+          git add .
+          git commit -m 'libs: mach: update to latest main revision'
+          git push -u origin HEAD