Subtle misc. refactors and lint suggestions

[mwtoews]

This PR has several miscellaneous refactors and applied lint suggestions via ruff check rules:

• Apply pydocstyle rules with "google" convention; these changes were mostly automated with a few manual edits for line lengths
• Apply isort (I) rule
• Apply pyupgrade (UP) rule, which uses format() instead of % formats
• Better use of pytest.approx() rather than assert round(... expressions

The only subtle change in this PR that is arguably not a refactor is to __new__, which will enforce float types. For instance, before this was the behavior:

>>> import numpy as np
>>> from affine import Affine
>>> Affine(*np.arange(6, dtype=np.float32))
Affine(np.float32(0.0), np.float32(1.0), np.float32(2.0),
       np.float32(3.0), np.float32(4.0), np.float32(5.0))

now with this PR the properties are all Python-native float types.

>>> Affine(*np.arange(6, dtype=np.float32))
Affine(0.0, 1.0, 2.0,
       3.0, 4.0, 5.0)

[mwtoews]

The previous CI error is because ubuntu-latest was switching to ubuntu-24.04, so pinning back to ubuntu-22.04 for now.

[sgillies]

Cool! There are a couple changes I'd like to see.

[sgillies]

Thanks @mwtoews ! Anything else?

[mwtoews]

I think that's it! Expect a docstyle PR soonish.