Adjust tests for Windows environments

[Zeitsperre]

Pull Request Checklist:

• This PR addresses an already opened issue (for bug fixes / features)
  • This PR addresses errors mentioned in Dynamic time selection #2055
• Tests for the changes have been added (for bug fixes / features)
  • (If applicable) Documentation has been added / updated (for bug fixes / features)
• CHANGELOG.rst has been updated (with summary of main changes)
  • Link to issue (:issue:number) and pull request (:pull:number) has been added

What kind of change does this PR introduce?

• Skips an encoding test that is not supported on Windows
• Allows connection to GitHub for an xarray test dataset required for one test.

Does this PR introduce a breaking change?

No.

Other information:

@baptistehamon if you have a minute, could you verify two things?

1. Does your development environment include pytest-socket?
2. Could you run the two affected tests here on your system to verify that they pass?

Thanks so much!

[baptistehamon]

Indeed, pytest-socket wasn't installed in my environment. I ran the pytest both with and without the module.

• Without the module installed, I had the following error when running the test on your PR:
  =================================== ERRORS ====================================
  _____________ ERROR collecting tests/test_sdba/test_adjustment.py _____________
  'enable_socket' not found in markers configuration option
  =========================== short test summary info ===========================
  ERROR tests/test_sdba/test_adjustment.py - Failed: 'enable_socket' not found in markers configuration option
  !!!!!!!!!!!!!!!!!!! Interrupted: 1 error during collection !!!!!!!!!!!!!!!!!!!!
  ============================== 1 error in 9.65s ===============================

• With the module, I still had the same error/fails on my PR but your PR fixes it !

Thanks!