release 2.1.0

Prepare 2.1 (#13)

* Update CICD
* Update CHANGELOG.md
* Add TZ (UTC) in output data (#12)
* fix:add utc=true to datetime
* fix:indentation
* Fix: add UTC index in tests
* Update output in README.md
* Fix: opsplanning is now timezone aware
* Fix tests in opsplanning
---------

Co-authored-by: Nouhayla BAHADDOU <nbahaddo@IFREMER.FR>

* Update CHANGELOG.md
* Update check.yml
* Update copyright date
* Bump version in CITATION.cff
* Update publish-to-pypi.yml
---------

Co-authored-by: Nouhayla BAHADDOU <nbahaddo@IFREMER.FR>