CI: not retrigger CI when PR description is edited + autocancel previ…

…ous build (#950)

* remove no longer relevant comment

* trigger CI on default pull request events only

* Auto-cancel previous build workflows

* prettier

.github/workflows/build.yml

@@ -5,11 +5,8 @@ name: Build
 # 2. It includes the PR/Commit text in the action item
 # 3. Artifacts are not available between workflows.
 
-# This is only allowing pushes on the moonbeam repo for pull requests.
-####### DO NOT CHANGE THIS !! #######
 on:
   pull_request:
-    types: [opened, edited, unassigned, synchronize]
   push:
     branches:
       - master

.github/workflows/cancel.yml

@@ -0,0 +1,13 @@
+name: Cancel
+on: [push]
+jobs:
+  cancel:
+    name: "Cancel Previous Build"
+    runs-on: ubuntu-latest
+    timeout-minutes: 3
+    steps:
+      - uses: styfle/cancel-workflow-action@0.9.1
+        with:
+          workflow_id: ".github/workflows/build.yml"
+          all_but_latest: true
+          access_token: ${{ github.token }}