Add Ubuntu 22.04 back to ci

[mcbarton]

Description

Please include a summary of changes, motivation and context for this PR.

This PR adds back Ubuntu 22.04 to the ci. Seems unlikely that one Ubuntu would be broken, and another ok, but it does happen with some sometimes. This PR allows us to be certain it hasn't happened to xeus-cpp.

Fixes # (issue)

Type of change

Please tick all options which are relevant.

• Bug fix
• New feature
• Added/removed dependencies
• Required documentation updates

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.80%. Comparing base (0a3a75e) to head (d354874).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #197   +/-   ##
=======================================
  Coverage   80.80%   80.80%           
=======================================
  Files          19       19           
  Lines         974      974           
  Branches       93       93           
=======================================
  Hits          787      787           
  Misses        187      187