Add f-string format and check with flynt for the whole codebase

[edumucelli]

Hi,

In order to standardize the f-string usage of the whole codebase I have added flynt to the format and lint scripts. This avoids multiple "f-string" one line pull requests and makes it go into the github check process to avoid introduction of old style string formatting once merged.

The reformatting was all made by flynt. I am not using flynt's --aggressive to avoid "conversions with potentially changed behavior".

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[edumucelli]

Thanks for the PR. I would prefer updating the codebase without adding a regular check.

Thanks for the prompt review. I have made the required changes, i.e., removed flynt from the shell/lint.sh and shell/format.sh and from the project requirements.txt.

[fchollet]

This branch has conflicts that must be resolved

Please rebase to fix conflict.

[edumucelli]

This branch has conflicts that must be resolved

Please rebase to fix conflict.

Sure, done.