Skip concurrent downstream tests (#208)

Author: jishnub

.github/workflows/downstream.yml

@@ -3,12 +3,20 @@ on:
   push:
     branches: [master]
     tags: [v*]
+    paths-ignore:
+      - 'LICENSE'
+      - 'README.md'
+      - '.github/workflows/TagBot.yml'
   pull_request:
     paths-ignore:
       - 'LICENSE'
       - 'README.md'
       - '.github/workflows/TagBot.yml'
 
+concurrency:
+  group: build-${{ github.event.pull_request.number || github.ref }}-${{ github.workflow }}
+  cancel-in-progress: true
+
 jobs:
   pre_job:
     # continue-on-error: true # Uncomment once integration is finished