ci: call infra's reusable update-infra workflow (#68)

Replaces the inline steps in infra-update.yml with a call to infra's reusable update-infra.yml workflow (added in infra v1.3.0). The triggers, concurrency and the per-repo INFRA_BOT_APP_ID / INFRA_BOT_PRIVATE_KEY setup stay the same; the token, checkout and PR steps now live in infra, so fixes reach this repo through @v1.

Author: ptsouchlos

.github/workflows/infra-update.yml

@@ -11,17 +11,7 @@ concurrency: infra-update
 
 jobs:
   update:
-    runs-on: ubuntu-latest
-    steps:
-      - id: app
-        uses: actions/create-github-app-token@v2
-        with:
-          app-id: ${{ vars.INFRA_BOT_APP_ID }}
-          private-key: ${{ secrets.INFRA_BOT_PRIVATE_KEY }}
-      - uses: actions/checkout@v7
-        with:
-          token: ${{ steps.app.outputs.token }}
-      - uses: ptsouchlos/infra/.github/actions/update-infra@v1
-        with:
-          token: ${{ steps.app.outputs.token }}
-          tag: ${{ github.event.client_payload.tag }}
+    uses: ptsouchlos/infra/.github/workflows/update-infra.yml@v1
+    secrets: inherit
+    with:
+      tag: ${{ github.event.client_payload.tag }}