update cancel workflow

Author: strtgbb

.github/workflows/cancel.yml

@@ -6,7 +6,7 @@ env:
 
 on: # yamllint disable-line rule:truthy
   workflow_run:
-    workflows: ["PullRequestCI", "ReleaseBranchCI", "DocsCheck", "BackportPR"]
+    workflows: ["PR","PullRequestCI", "ReleaseBranchCI", "DocsCheck", "BackportPR"]
     types:
       - requested
 jobs: