OWS release 1.8.17

Urgent bug-fix release to address a WCS bug.

This release also contains a couple of minor backwards compatibility issues, see below for details.

Version 1.8.18 will probably follow fairly rapidly as there are a couple of other known issues that are actively being worked on, see below for details.

Changes:

• Cleanup/refactor of styles package: docstrings, type-hints, cleanup and improved test coverage (#695)
• Change default behaviour of $AWS_NO_SIGN_REQUEST to match the standard default behaviour for boto3-based applications (#696)
• Fix WCS queries against layers with a flag-band in the main product (#699)
• Increment version number (#700)

Backward Incompatibilities

1. #695 removed support for some legacy legend config formats that have been deprecated (and undocumented) for over a year.
2. #696 changes the default behaviour if $AWS_NO_SIGN_REQUEST is not set. Previously the default behaviour was unsigned requests, it is now signed requests. This was a necessary first-step to supporting dynamic credentials for S3 access, and brings OWS into line with other software using boto3 for S3 access.

Known Issues

1. There are still issues with WCS queries against layers with a flag-band in the main product. These will be addressed in the next release and should not effect queries generated by the Terria Export function.
2. Dynamic credentialling for S3 access is still problematic. We have a PR almost ready to merge (#697) but it needs further testing.