[1.9.1]
Update grav to 1.7.52
Full Changelog
GPM client now sends the running PHP version with index requests so the server can substitute PHP-aware compat fallbacks when a plugin's latest release requires a newer PHP than the client can run.
[security] Extended default uploads_dangerous_extensions to include md, yaml, yml, json, twig, ini page-content extensions that can be weaponised via permissive form-upload accept policies (GHSA-w4rc-p66m-x6qq, defense-in-depth alongside the Form 9.1.0 plugin fix).
Added foundation for migrating to Grav 2.0: cross-major auto-upgrades are blocked in GPM, and core now surfaces a next_major hint so admin can point users at the new migrate-grav plugin
Added compatibility: blueprint support so plugins/themes can declare which Grav versions they support
Added self-upgrade preflight that flags incompatible plugins/themes and psr/log / Monolog conflicts before proceeding
Added upgrade resilience with automatic maintenance mode and opcache reset during self-upgrade
Added new cache-cleanup CLI command to prune obsolete cache entries
Added new onFlexDirectoryConfigBeforeSave event for Flex
More readable time output in bin/grav logviewer #4009
Fixed selectize field losing values when keyed options were used