[Bug] Conversion from `u64::MAX` into `RedisValue` fails about fred.rs HOT 1 OPEN

Yeah, I'm not sure there's a great solution here. The representation for numbers in redis and on the wire is a signed 64-bit integer, so I intentionally made anything >2^63 fail the automatic type conversion to avoid this kind of thing:

redis-main:6379> set foo 18446744073709551616
OK
redis-main:6379> decr foo
(error) ERR value is not an integer or out of range

If you're only operating on the value as a number in app code then I can see why this would be annoying, but the alternative approach of hiding a to_string, and thereby implicitly changing the allowed operations on the server, seemed worse in my opinion. The intention here was to make it explicit to the user that the underlying value must be stored and operated on as a string on the server.

from fred.rs.