Artiweb comment workflow (#3047)

As discussed, not sure how to test this.

.github/workflows/artiweb.yml

@@ -0,0 +1,18 @@
+on:
+  pull_request:
+    types: [opened, reopened]
+
+jobs:
+  comment:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/github-script@v5
+        with:
+          github-token: ${{secrets.GITHUB_TOKEN}}
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: `Test artifacts will be available on [Artiweb](https://keyproject.github.io/artiweb/${context.issue.number}/).`
+            })