Apply fixes for linting issues

[peytondmurray]

This PR applies pre-commit fixes across the entire repository in preparation for merging #40. Although this touches many files, the fixes are all safe, and were generated with ruff --fix. Most of these are end-of-file and trailing whitespace fixes, but there are also a few places imports were reordered, and where f-strings were used in place of calls to format().

[hassler-google]

Hi Peyton, thanks for your contribution here.

For this PR and #38, the main thing we must figure out is how to handle the difference in the linter and documentation format between this repository and the place from which we publish changes here.

For example, the upstream repository uses a variant of pylint for linting instead of ruff, and we will need to maintain a version with pylint: https://google.github.io/styleguide/pyguide.html.

For this PR, do most of the changes go away if we set a linter check using pylint instead of ruff --fix ?

[peytondmurray]

ruff has many rules available to enable, and pylint's rules have overlap with a lot of ruff rules.

ruff has near to complete compatibility with the rest of Python's lint tool ecosystem, except it is far, far faster, and configuration lives in one place - which makes pre-commit hooks much more pleasant to use. If at all possible I'd encourage a move to ruff; many projects in the python scientific ecosystem have done so, and it makes linting a breeze.

That said, many of the changes that you see here come from the end-of-file-fixer and trailing-whitespace pre-commit hooks, which ensure that every file ends with a newline and that useless whitespace is removed (blank spaces at the end of lines, and spaces on blank lines). Those changes have nothing to do with ruff rules, but they're good practice anyway.