Use label-check and attach-next-milestone-action (#492)

.github/workflows/label-check.yml

@@ -0,0 +1,19 @@
+name: Labels
+
+on:
+  pull_request:
+    types:
+      - opened
+      - labeled
+      - unlabeled
+
+env:
+  LABELS: ${{ join( github.event.pull_request.labels.*.name, ' ' ) }}
+
+jobs:
+  check-type-label:
+    name: ensure type label
+    runs-on: ubuntu-latest
+    steps:
+      - if: "contains( env.LABELS, 'type: ' ) == false"
+        run: exit 1

.github/workflows/milestone-merged-prs.yml

@@ -0,0 +1,18 @@
+name: Milestone
+
+on:
+  pull_request_target:
+    types:
+      - closed
+    branches:
+      - "main"
+
+jobs:
+  milestone_pr:
+    name: attach to PR
+    runs-on: ubuntu-latest
+    steps:
+      - uses: scientific-python/attach-next-milestone-action@bc07be829f693829263e57d5e8489f4e57d3d420
+        with:
+          token: ${{ secrets.MILESTONE_LABELER_TOKEN }}
+          force: true