Update scorecard workflow (#1196)

Add back `workflow_call` trigger that must have been removed
accidentally in a previous update.

Author: mhucka

.github/workflows/scorecard-scanner.yaml

@@ -38,6 +38,17 @@ on:
         type: boolean
         default: true
 
+  # Allow calling from nightly.yaml.
+  workflow_call:
+    inputs:
+      reason:
+        description: 'Append text to workflow run name:'
+        type: string
+      debug:
+        description: 'Run with debugging options'
+        type: boolean
+        default: false
+
 concurrency:
   # Cancel any previously-started but still active runs on the same branch.
   cancel-in-progress: true