remove 3.7 in github python workflow (#19098)

Author: wing328

.github/workflows/samples-python-petstore.yaml

@@ -15,7 +15,6 @@ jobs:
       fail-fast: false
       matrix:
         python-version:
-          - "3.7"
           - "3.8"
           - "3.9"
           - "3.10"