Add GitHub Action to comment on PRs with Binder link to try out changes (#261)

* Add GitHub Action to comment on PRs with Binder link to try out changes

* Fix token

* Fall back to using Actions bot instead of Dask bot

* Switch back to Dask bot

* Run on PR target instead of PR

Author: jacobtomlinson

.github/workflows/ci-binder-link-comment.yaml

@@ -0,0 +1,19 @@
+name: Comment with Binder link on PRs
+
+on: pull_request_target
+
+jobs:
+  binder_link_comment:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Comment PR
+        uses: thollander/actions-comment-pull-request@v1
+        with:
+          message: |
+            Beep boop! Here is a Binder link where you can try out this change.
+            [![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/${{github.repository}}/${{github.ref}})
+          comment_includes: "Binder link"
+          GITHUB_TOKEN: ${{ secrets.DASK_BOT_TOKEN }}