Add workflow to assign v3 project and milestone

Author: ReneWerner87

.github/workflows/v3-label-automation.yml

@@ -0,0 +1,51 @@
+name: Assign v3 project and milestone
+
+on:
+  issues:
+    types:
+      - labeled
+  pull_request:
+    types:
+      - labeled
+
+permissions:
+  contents: read
+  issues: write
+  pull-requests: write
+  projects: write
+
+jobs:
+  assign-v3:
+    if: github.event.label.name == 'v3'
+    runs-on: ubuntu-latest
+    steps:
+      - name: Add item to v3 project
+        uses: actions/add-to-project@v0.5.0
+        with:
+          project-url: ${{ vars.V3_PROJECT_URL }}
+          github-token: ${{ secrets.PROJECT_V3_TOKEN }}
+      - name: Assign v3 milestone
+        uses: actions/github-script@v7
+        with:
+          github-token: ${{ secrets.PROJECT_V3_TOKEN }}
+          script: |
+            const core = require('@actions/core');
+            const payload = context.eventName === 'issues' ? context.payload.issue : context.payload.pull_request;
+            const issueNumber = payload.number;
+            const { data: milestones } = await github.rest.issues.listMilestones({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              state: 'open',
+              per_page: 100,
+            });
+            const milestone = milestones.find((item) => item.title === 'v3');
+            if (!milestone) {
+              core.setFailed('Milestone "v3" was not found.');
+              return;
+            }
+            await github.rest.issues.update({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: issueNumber,
+              milestone: milestone.number,
+            });