[MCL-11294] Launcher logs "Deserializing account" warnings

The bug

The launcher logs the following warnings into .minecraft/launcher_log.txt:

[Warning: 2019-06-30 19:35:20.8782984: EndpointAPI.cpp(108)] Deserializing account response.user.dateOfBirth: Unknown key
[Warning: 2019-06-30 19:35:20.8882984: EndpointAPI.cpp(108)] Deserializing account response.user.emailSubscriptionKey: Unknown key
[Warning: 2019-06-30 19:35:20.8882984: EndpointAPI.cpp(108)] Deserializing account response.user.emailSubscriptionStatus: Unknown key
[Warning: 2019-06-30 19:35:20.8882984: EndpointAPI.cpp(108)] Deserializing account response.user.migratedAt: Unknown key
[Warning: 2019-06-30 19:35:20.8882984: EndpointAPI.cpp(108)] Deserializing account response.user.migratedFrom: Unknown key
[Warning: 2019-06-30 19:35:20.8882984: EndpointAPI.cpp(108)] Deserializing account response.user.migrationId: Unknown key
[Warning: 2019-06-30 19:35:20.8882984: EndpointAPI.cpp(108)] Deserializing account response.user.passwordChangedAt: Unknown key
[Warning: 2019-06-30 19:35:20.8882984: EndpointAPI.cpp(108)] Deserializing account response.user.registeredAt: Unknown key