CD via GitHub Actions

[iainrussell]

Description

Enables deployment on internal conda, HPC, source tarball and GitHub release via tag.

Contributor Declaration

By opening this pull request, I affirm the following:

• All authors agree to the Contributor License Agreement.
• The code follows the project's coding standards.
• I have performed self-review and added comments where needed.
• I have added or updated tests to verify that my changes are effective and functional.
• I have run all existing tests and confirmed they pass.

🌦️ >> Documentation << 🌦️
https://sites.ecmwf.int/docs/dev-section/ecflow/pull-requests/PR-279

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 49.29%. Comparing base (70ef1c8) to head (eeaee9a).
⚠️ Report is 24 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #279   +/-   ##
========================================
  Coverage    49.28%   49.29%           
========================================
  Files         1233     1233           
  Lines        97801    97801           
  Branches     14874    14875    +1     
========================================
+ Hits         48201    48209    +8     
+ Misses       49600    49592    -8     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[iainrussell]

@marcosbento, ready for review/merge!

[iainrussell]

Will be superseded by another PR