Breaking:

• The extension for mbtiles used in MapProxy was wrong. It used .mbtile instead of .mbtiles. Existing files in
  caches have to be renamed! Here is a small script to change all files in a directory recursively:
  find . -type f -name "*.mbtile" -exec sh -c 'mv "$1" "${1%.mbtile}.mbtiles"' _ {} \;
• lxml was updated. The new version is much stricter in its inputs and administrators might have to adjust
  featureinfo services to output valid HTML.

Improvements:

• New source types ogcapitiles and ogcapimaps are now available! See docs for further information.
• New util gridconf-from-ogcapitilematrixset to fetch grids from an OGC API compliant web service was added.
  See docs for further information.
• MapProxy now offers an OGCAPI compliant service for OGC API Maps and OGC API Tiles. Including landing page and
  preview maps! See docs for further information.
• The SERVICE parameter for WMS GetMap requests is no longer mandatory as according to spec.
• Added test pipeline for the documentation.
• The GitHub actions now have better fitting permissions, improving the security.
• WMTS capabilities now include OperationsMetadata for restful mode.
• TMS capabilities now include metadata similar to WMS and WMTS.

Maintenance:

• Some fixes in the documentation.
• As shapely is no longer optional, code to check for its existence has been removed.

Fixes:

• An error regarding unicode strings in the featureinfo parsing was fixed.
• An error in the debug logging of configurations was fixed

What's Changed

• fix(ows): make service non mandatory for WMS GetMap requests by @simonseyock in #1292
• Doc: fix warnings, and build doc as part of pull requests with warnings as errors by @rouault in #1266
• lint.yml and test.yml: set read permission only, and add concurrency … by @rouault in #1267
• Add ogcapitiles and ogcapimaps source types by @rouault in #1268
• Use correct command for Waitress serve by @symroe in #1294
• fix error: ValueError: Unicode strings with encoding declaration by @MarkusAlbrechtSWM in #1271
• restful encoding / style isdefault and urn:ogc:def:crs for SupportedCRS by @hschiebold in #1186
• chore(deps): bump pluggy from 1.5.0 to 1.6.0 by @dependabot[bot] in #1261
• chore(deps): bump github/codeql-action from 3 to 4 by @dependabot[bot] in #1303
• fix: using correct extension for mbtiles by @simonseyock in #1251
• feat: remove code that makes shapely optional by @simonseyock in #1180
• Update lxml by @simonseyock in #1306
• chore(deps): bump pyasn1 from 0.5.1 to 0.6.1 by @dependabot[bot] in #1308
• Optional tms metadata by @hschiebold in #1160
• Add support for OGC API Maps and Tiles service (server side) by @rouault in #1284
• Add some license headers and files by @weskamm in #1314
• fix: do not sort keys of debug config output by @simonseyock in #1325
• dev: prepare 6.0.0 release by @simonseyock in #1327

New Contributors

• @symroe made their first contribution in #1294
• @MarkusAlbrechtSWM made their first contribution in #1271

Full Changelog: 5.1.1...6.0.0