Pyspeedinsights

Adds some sitemap enhancements, most notably sitemap index support.

* Feature: Add support for sitemap index detection. If a sitemap index is detected, the package will recursively gather the URLs listed in each sitemap in your sitemap index and include them in requests. If a standard sitemap file is passed, only that sitemap will be processed.
* Bug fix: Add a dummy user-agent to avoid being blocked by firewalls (e.g. CloudFlare returns a 403 if it detects the default requests user-agent)
* Code quality: use truthy/falsy return value for validating sitemap URL extension rather than an explicit `is True`

Contains a minor bug fix and fallback for keyring.

- Bug fix: avoid using `:` to separate timestamps in report filenames as this is an invalid filename character. Prevented reports from being saved correctly on Windows.
- Minor enhancement: add a manual input fallback in the event of an empty API key in keyring or keyring errors. Makes using keyring optional by allowing users to manually enter their API key at runtime.
- Some minor development workflow enhancements

This is the initial release but the package is currently untested.