Fix sha in commit message

Signed-off-by: Naren Dasan <[email protected]>
Signed-off-by: Naren Dasan <[email protected]>

Author: narendasan

.github/workflows/docgen.yml

@@ -33,7 +33,7 @@ jobs:
         with:
         # Required
           commit_message: >
-            docs: [Automated] Regenerating documenation from ${{github.head_ref}}
+            docs: [Automated] Regenerating documenation from $GITHUB_SHA
           commit_options: "--no-verify --signoff"
           file_pattern: docs/
           commit_user_name: TRTorch Github Bot