PR Summary

I'm guessing 99.9% of the use of gridspec_kws is to set the height or width ratios of axes. And it is pretty esoteric to ask people to know about gridspecs in order to access this. Here we add width_ratios and height_ratios to the subplots and subplot_mosaic calls.

Previously we would do

fig, axs = plt.subplots(1, 2, gridspec_kw={'width_ratios': [1, 2]})

This PR allows

fig, axs = plt.subplots(1, 2, width_ratios=[1, 2])

PR Checklist

Tests and Styling

• Has pytest style unit tests (and pytest passes).
• Is Flake 8 compliant (install flake8-docstrings and run flake8 --docstring-convention=all).

Documentation

• New features are documented, with examples if plot related.
• New features have an entry in doc/users/next_whats_new/ (follow instructions in README.rst there).
• API changes documented in doc/api/next_api_changes/ (follow instructions in README.rst there).
• Documentation is sphinx and numpydoc compliant (the docs should build without error).