Check off some of the minor items on Scientific Python review

[mwcraig]

Let's do these items from this review:

• VPP001: `Validate pyproject.toml Invalid pyproject.toml! Error: project.license must be valid exactly by one definition
• PY005: Has tests folder. Projects must have a folder called test or src/*/test -- not sure why this is failing -- couldn't figure out why this passes for astropy but not for stellarphot since the structure is the same -- See Consider changing location of test directory #200 instead.
• PP308: Specifies useful pytest summary
• PP309: Filter warnings specified filterwarnings must be set (probably to at least ["error"]). Python will hide important warnings otherwise, like deprecations. -- skip for now as this means fixing all warnings
• GH200: Maintained by Dependabot -- add a dependabot.yml to update actions automatically.
• GH102: Auto-cancel on repeated PRs. At least one workflow should auto-cancel.