Add quotes around "on" to ignore yamllint error

I think this is a bug where yamllint sees "on" property as a truthy/falsy value and gives an error

Author: JamyGolden

.github/workflows/auto-assign-issues.yml

@@ -1,6 +1,6 @@
 name: Auto assignment for issues
 
-on:
+"on":
   issues:
     types: [opened]
 

.github/workflows/test.yml

@@ -1,5 +1,5 @@
 name: Test
-on:
+"on":
   pull_request:
     branches:
       - "spec-**"