deprecate the gender property from the protocol entirely (#4496)

* deprecate the gender property from the protocol entirely

* use obsolete instead of deprecated

* add the database migration

* update internal database version as well

webclient/src/types/user.tsx

@@ -3,7 +3,6 @@ export interface User {
   name: string;
   privlevel: UserAccessLevel;
   userLevel: UserPrivLevel;
-  gender?: number;
   realName?: string;
   country?: string;
   avatarBmp?: Uint8Array;