Prepare changelog for v0.13.0-rc.3
Prepare changelog for v0.13.0-rc.3

vector-im/vector-web,martindale/vector,martindale/vector,vector-im/vector-web,vector-im/riot-web,vector-im/riot-web,vector-im/riot-web,vector-im/riot-web,vector-im/vector-web,vector-im/riot-web,vector-im/vector-web,vector-im/riot-web,vector-im/vector-web