Update Sodium Compat to 1.17.1 (PHP 8.1 compatibility)

[jrf]

Sodium_Compat 1.17.1 has just been released and includes further improvements for PHP 8.1 compatibility.

The version included with WP should be updated.

Full details:

• ​https://github.com/paragonie/sodium_compat/releases/tag/v1.17.1
• ​https://github.com/paragonie/sodium_compat/compare/v1.17.0...v1.17.1

I've reviewed the diff and would strongly recommend an update at the earliest convenience.

Previously: #48371, #51399, #51925, #53274, #53907
Related: #54730

[SergeyBiryukov]

In 52988:

Upgrade/Install: Update sodium_compat to v1.17.1.

The latest version of sodium_compat includes further improvements for PHP 8.1 compatibility.

Release notes:
​https://github.com/paragonie/sodium_compat/releases/tag/v1.17.1

A full list of changes in this update can be found on GitHub:
​https://github.com/paragonie/sodium_compat/compare/v1.17.0...v1.17.1

Follow-up to [49741], [51002], [51591].

Props jrf, paragoninitiativeenterprises.
Fixes #55453.

[milana_cap]

Marking for dev note but really needs only mentioning in Field guide.