Bump mautrix-python version

requirements.txt

@@ -4,6 +4,6 @@ alembic>=1,<2
 ruamel.yaml>=0.15.94,<0.17
 commonmark>=0.8,<0.10
 python-magic>=0.4,<0.5
-mautrix>=0.7.2,<0.8
+mautrix>=0.7.3,<0.8
 fbchat-asyncio>=0.6.19,<0.7
 prometheus_client>=0.6,<0.9