Update ossf.yaml

Author: Tyler Titsworth

.github/workflows/ossf.yaml

@@ -7,7 +7,7 @@ on:
   # For Branch-Protection check. Only the default branch is supported. See
   # https://github.com/ossf/scorecard/blob/main/docs/checks.md#branch-protection
   branch_protection_rule:
-  pull_request:
+  workflow_dispatch:
   # To guarantee Maintained check is occasionally updated. See
   # https://github.com/ossf/scorecard/blob/main/docs/checks.md#maintained
   schedule: