Mautrix

* *(crypto)* Fixed bug with redacting megolm sessions when device is deleted.

* *(bridge)* Fixed backwards-compatibility with new key deletion config options.

* *(crypto)* Fixed bug in previous release which caused errors if the `max_age`
of a megolm session was not known.
* *(crypto)* Changed key receiving handler to fetch encryption config from
server if it's not cached locally (to find `max_age` and `max_messages` more
reliably).

* *(crypto, bridge)* Added options to automatically ratchet/delete megolm
sessions to minimize access to old messages.

* *(crypto)* Fixed bug in crypto store migration when using outbound sessions
with max age higher than usual.

* *(crypto)* Updated crypto store schema to match mautrix-go.
* *(types)* Fixed `set_thread_parent` adding reply fallbacks to the message body.