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* Allow client to use external Session object by lavigne958 in https://github.com/burnash/gspread/pull/1384
* Remove-py-3.7-support by alifeee in https://github.com/burnash/gspread/pull/1396
* bugfix/client export by lavigne958 in https://github.com/burnash/gspread/pull/1392
* Fix oauth flow typo by alifeee in https://github.com/burnash/gspread/pull/1397
* check oauth creds type using `isinstance` by alifeee in https://github.com/burnash/gspread/pull/1398
* Fix type hints at find method in worksheet.py by deftfitf in https://github.com/burnash/gspread/pull/1407
* Fixup get empty cell value is `None` by lavigne958 in https://github.com/burnash/gspread/pull/1404
* Fix missing attribute `spreadsheet` in `Worksheet`. by lavigne958 in https://github.com/burnash/gspread/pull/1402
* update migration guide by alifeee in https://github.com/burnash/gspread/pull/1409