Update main_py_to_bitly.yml

Author: skysign

.github/workflows/main_py_to_bitly.yml

@@ -9,7 +9,7 @@
         output1: ${{ steps.step1.outputs }}
       steps:
         - id: step1
-          run: git diff --name-only HEAD~1 HEAD | grep '/main.py'
+          run: git diff --name-only HEAD^ HEAD | grep '/main.py'
     job2:
       needs: job1    
       runs-on: ubuntu-latest