fix(deps): update module maunium.net/go/mautrix to v0.15.4

[renovate]

This PR contains the following updates:

Package	Type	Update	Change
maunium.net/go/mautrix	require	patch	v0.15.3 -> v0.15.4

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Release Notes

mautrix/go (maunium.net/go/mautrix)

v0.15.4

Compare Source

• (client) Deprecated MSC2716 methods and added new Beeper-specific batch
  send methods, as upstream MSC2716 support has been abandoned.
• (client) Added proper error handling and automatic retries to media
  downloads.
• (crypto, bridge) Added option to remove all keys that were received before
  the automatic ratcheting was implemented (in v0.15.1).
• (dbutil) Added JSON utility for writing/reading arbitrary JSON objects to
  the db conveniently without manually de/serializing.

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[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (79e26e5) 74.10% compared to head (6e9288e) 74.10%.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #639   +/-   ##
=======================================
  Coverage   74.10%   74.10%           
=======================================
  Files          44       44           
  Lines        1572     1572           
=======================================
  Hits         1165     1165           
  Misses        307      307           
  Partials      100      100           

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