Add .NET 8 support for Authentication.JwtBearer.Google

[anssiv]

In .NET 8 there is a breaking change that the Authentication.JwtBearer.Google is affected by.

At the very least, you should include documentation specifying that UseSecurityTokenValidators=true is now a required configuration.

.AddJwtBearer(options => 
{
    options.UseSecurityTokenValidators = true;
    options.UseGoogle("...");
});

[khellang]

Ah, thanks for the heads up! I'll push a new version as soon as possible. Wanna send a PR? 😇