Fix oauth flow typo

[alifeee]

closes #1394

Firstly, this fixes the typo scopres -> scopes

Secondly, it changes the typing from Callable to Protocol, so that this issue is caught by the mypy linting. e.g., in this workflow

Found 1 error in 1 file (checked 10 source files)
gspread/auth.py:284: error: Unexpected keyword argument "scopres" for "__call__" of "FlowCallable"; did you mean "scopes"?  [call-arg]
lint: exit 1 (4.30 seconds) /home/runner/work/gspread/gspread> mypy --install-types --non-interactive --ignore-missing-imports ./gspread pid=1957