Add nightly build

[mcbarton]

Description

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

This PR will allow xeus-cpp will add a nightly build to the ci, to make sure nothing breaks each night due to a dependency being upgraded which was unpinned for example. It will also allow the deployment to pick up the latest changes in its dependencies to have new features.

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 80.72%. Comparing base (e5de72b) to head (e84c74b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #240   +/-   ##
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  Coverage   80.72%   80.72%           
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  Files          19       19           
  Lines         970      970           
  Branches       93       93           
=======================================
  Hits          783      783           
  Misses        187      187