Improve error message on replay data mismatch (#3385)

This improves the error message when replay data do not match the actual
request by stating the replay data file and line:

Replay data mismatch in
PyGithub/tests/ReplayData/Team.testGetTeams.txt:5

```
>       assert self.__splitUrl(url) == self.__splitUrl(self.__readLine()), self.__replayDataMismatchFilePos()
E       AssertionError: Replay data mismatch in /home/enrico/git/PyGithub/tests/ReplayData/Team.testGetTeams.txt:5
E       assert ['/organizati...345678/teams'] == ['/organizati...345679/teams']
E         
E         At index 0 diff: '/organizations/1234567/team/12345678/teams' != '/organizations/1234567/team/12345679/teams'
E         Use -v to get more diff

tests/Framework.py:279: AssertionError
```