Use f-strings instead of `str.format`

[MarieRoald]

Currently, TensorLy uses the format-method for string formatting. However, in Python 3.6, f-strings were introduced, so the only reason to use the format-method instead of f-strings is for support of Python 3.5, which reached end-of-life in 2020. We can therefore safely replace all calls to str.format with f-strings, which is more readable. See example below:

x = 1.
s1 = "{}".format(x)
s2 = f"{x}"

s3 = "{:.1f}".format(x)
s4 = f"{x:.1f}"

print(s1 == s2)
print(s3 == s4)

True
True

More information is available in this tutorial: https://realpython.com/python-f-strings/

[bakhtos]

Hello! I volunteer to take care of this issue.

[JeanKossaifi]

Great, thanks @bakhtos and welcome to the project!

[aarmey]

This should be complete!