`word_generator()` changes

[znarfm]

This pull request includes several improvements to the word_generator function in the bing_rewards/__init__.py file. The changes enhance error handling, ensure uniform random distribution, and improve code readability.

Enhancements to word_generator function:

• Type hints: specified the return type as Generator[str, None, None].
• Added yields and potential exceptions in the docstring.
• Implemented error handling for FileNotFoundError and IOError, with appropriate error messages and re-raising of exceptions.
• Ensured the function handles empty keyword files by raising a ValueError if the file size is zero. (Useful when implementing a feature to add your own .txt files for searches)
• Improved the random starting position logic (to capture the whole txt file) and ensured clean line boundaries by discarding partial lines and skipping empty lines.

[jack-mil]

Ah, thanks for the contribution. Reading from the file always felt like a bit of a hack to me, and I didn't love my implementation. I will take a look and try this when I have a chance.

If any of the Ruff linting errors seem unreasonable or unnecessary, I am open to disable or ignoring those errors. I kind of went overly zealous when setting up Ruff and configuring errors. Selecting almost everything is probably unnecessary, I was mostly interested in what Ruff would detect.

[znarfm]

Mostly was just errors about using double quotes. Sorry, ruff linting is kinda new for me.

[jack-mil]

you should be able to set up your editor to auto format with Ruff using the project.toml config. Or use the ruff executable directly. Or even use the pre-commit hook. it's up to you