finally got the expected result by using Graphql.here is the complete code

def run_query(query): # A simple function to use requests.post to make the API call. Note the json= section.
    try:
        request = requests.post('https://api.github.***.com/graphql', json={'query': query}, headers=headers)
        return request.json()
    except e:
        returnVal = '404'
        query = """
                    {
                      repository(owner: \""""+ownerVal+"""\", name: \""""+repoVal+"""\") {
                        object(expression: \""""+branchVal+"""\") {
                          ... on Commit {
                            blame(path: \""""+folderVal+"/"+data['name']+"""\") {
                              ranges {
                                commit {
                                  committedDate
                                }
                              }
                            }
                          }
                        }
                      }
                    }
                    """

result = run_query(query)
commit_date = result["data"]["repository"]["object"]["blame"]["ranges"][0]["commit"]["committedDate"]