x/crypto/argon2: Update recommended parameters

[ryicoh]

https://github.com/golang/crypto/blob/2c476679df9a5c6279ec05b48165f4bed48b792e/argon2/argon2.go#L86

// The draft RFC recommends[2] time=1, and memory=64*1024 is a sensible number.

The current document recommends time=1 based on the RFC draft,
but RFC 9106 published in September 2021 recommends time=3.

The Argon2id variant with t=3 and 64 MiB memory is the SECOND
RECOMMENDED option and is suggested as a default setting for memory-
constrained environments.

[seankhliao]

cc @golang/security