Adding the GH action permission to entire workflow

- Update the content permission to `write` for testTKG joob

Signed-off-by: Anna Babu Palathingal <anna.bp@ibm.com>

.github/workflows/testTKG.yml

@@ -2,6 +2,10 @@ name: "Run TKG Tests"
 on:
   issue_comment:
     types: [created]
+permissions:
+    contents: write
+    issues: write
+    pull-requests: write
 jobs:
   testTKG:
     permissions: