v0.8 - overridable `get_client_root_url` and Wagtail 6

The main change is that get_client_root_url is overridable on your page model inheriting from our mixins. The method takes the request parameter.

What's Changed

• Update API view endpoint in README.md by @ElectronicRU in #56
• [pre-commit.ci] pre-commit autoupdate by @pre-commit-ci in #55
• Tooling updates and tests against Wagtail 6.0 by @zerolab in #60 and @katdom13 in #62
• Make get_client_root_url overridable both in both mixins by @zerolab in #59

New Contributors

• @ElectronicRU made their first contribution in #56
• @katdom13 made their first contribution in #62

Full Changelog: v0.7.0...v0.8