Support SHA-256 hash in libravatar URLs

Support for using SHA-256 hash for URLs for libravatar as per https://wiki.libravatar.org/api/ .

Note: Gravatar does not support for SHA-256 hash but only for MD5 (as of 2022-08).

This feature enhancement helps GitLab work in FIPS mode.

Update 2024-01-22

Gravatar now supports SHA256, so you can just use the same digest for both.

Source: https://docs.gravatar.com/general/hash/

It should be feasible to just migrate over the SHA256 without issues in either:

• Gravatar is a centralized service, so there is no concern there.
• Libravatar has had SHA256 support since 2018, so even for self-hosted instances, it should be a relatively safe move. [source]

Resources

• Gravatar: https://en.wikipedia.org/wiki/Gravatar