enable passing endpoint to test-examples workflow

Author: robtaylor

.github/workflows/test-examples.yml

@@ -7,6 +7,10 @@ on:
         required: false
         type: string
         default: ''
+      CHIPFLOW_ENDPOINT:
+        required: false
+        type: string
+        default: ''
     secrets:
       CHIPFLOW_API_KEY:
         required: true