v0.15.0-beta.3

• Breaking change (appservice) Removed Load() and AppService.Init() functions. The struct should just be created with Create() and the relevant fields should be filled manually.
• Breaking change (appservice) Removed public HomeserverURL field and replaced it with a SetHomeserverURL method.
• (appservice) Added support for unix sockets for homeserver URL and appservice HTTP server.
• (client) Changed request logging to log durations as floats instead of strings (using zerolog's Dur(), so the exact output can be configured).
• (bridge) Changed zerolog to use nanosecond precision timestamps.
• (crypto) Added message index to log after encrypting/decrypting megolm events, and when failing to decrypt due to duplicate index.
• (sqlstatestore) Fixed warning log for rooms that don't have encryption enabled.