Remove autosquash and add branch-cleanup

.github/workflows/autosquash.yml

@@ -1,40 +0,0 @@
-
-name: Autosquash
-on:
-  check_run:
-    types:
-      # Check runs completing successfully can unblock the
-      # corresponding pull requests and make them mergeable.
-      - completed
-  pull_request:
-    types:
-      # A closed pull request makes the checks on the other
-      # pull request on the same base outdated.
-      - closed
-      # Adding the autosquash label to a pull request can
-      # trigger an update or a merge.
-      - labeled
-  pull_request_review:
-    types:
-      # Review approvals can unblock the pull request and
-      # make it mergeable.
-      - submitted
-  # Success statuses can unblock the corresponding
-  # pull requests and make them mergeable.
-  status: {}
-
-jobs:
-  autosquash:
-    name: Autosquash
-    runs-on: ubuntu-18.04
-    steps:
-      - uses: tibdex/autosquash@v2
-        with:
-          # We can't use the built-in secrets.GITHUB_TOKEN yet because of this limitation:
-          # https://github.community/t5/GitHub-Actions/Triggering-a-new-workflow-from-another-workflow/td-p/31676
-          # In the meantime, use a token granting write access on the repo:
-          # - a GitHub App token
-          #   See https://github.com/marketplace/actions/github-app-token.
-          # - a personal access token
-          #   See https://help.github.com/en/articles/creating-a-personal-access-token-for-the-command-line.
-          github_token: ${{ secrets.AUTOSQUASH_TOKEN }}

.github/workflows/branch-cleanup.yml

@@ -0,0 +1,11 @@
+name: branch-cleanup
+on:
+  pull_request:
+    branches:
+      - dev
+jobs:
+  cleanup-branch:
+    name: on pull request merge, delete the branch
+    runs-on: ubuntu-latest
+    steps:
+    - uses: jessfraz/branch-cleanup-action@master