Update dependabot & nightly workflows

.github/dependabot.yml

@@ -1,40 +1,44 @@
 version: 2
 
 updates:
+  # Handle PyPI updates
   - package-ecosystem: pip
     directory: "/ci"
     schedule:
-      interval: daily
-      time: "06:00"
-      timezone: "America/Denver"
-
+      interval: weekly
     allow:
       - dependency-type: all
-
     open-pull-requests-limit: 10
     pull-request-branch-name:
       separator: "-"
     labels:
       - "Type: Maintenance"
+      - "Area: Infrastructure"
     commit-message:
-      prefix: "MNT: "
+      prefix: "CI: "
       include: "scope"
+    groups:
+      flake8:
+        patterns:
+          - "flake8*"
+          - "pycodestyle"
+          - "pyflakes"
 
+  # Update GitHub Actions versions in workflows
   - package-ecosystem: "github-actions"
     # Workflow files stored in the
     # default location of `.github/workflows`
     directory: "/"
     schedule:
-      interval: "daily"
-
+      interval: "weekly"
     allow:
       - dependency-type: all
-
     open-pull-requests-limit: 10
     pull-request-branch-name:
       separator: "-"
     labels:
       - "Type: Maintenance"
+      - "Area: Infrastructure"
     commit-message:
-      prefix: "MNT: "
+      prefix: "CI: "
       include: "scope"

.github/workflows/automerge-dependabot.yml

@@ -0,0 +1,24 @@
+name: Auto-merge Dependabot PRs
+
+on:
+  pull_request_target:
+
+jobs:
+  #
+  # Automatically review dependabot PRs and set them to automerge (on successful checks)
+  #
+  Automerge:
+    runs-on: ubuntu-latest
+    if: github.actor == 'dependabot[bot]'
+    env:
+      GH_TOKEN: ${{ github.token }}
+
+    permissions:
+      contents: write
+      pull-requests: write
+
+    steps:
+    - name: Set auto-merge
+      run: gh pr merge -R ${{ github.repository }} --merge --auto ${{ github.event.pull_request.number }}
+    - name: Review PR
+      run: gh pr review -R ${{ github.repository }} --approve ${{ github.event.pull_request.number }}

.github/workflows/nightly-builds.yml

@@ -2,8 +2,8 @@ name: Nightly Checks
 
 on:
   schedule:
-  # Runs at 09Z (3am MDT)
-    - cron: "0 9 * * 2"
+  # Runs at 0930Z (3am MDT)
+    - cron: "30 9 * * 2"
 
   # Allow a manual run
   workflow_dispatch: