Hotfix for issues 251 and 261

[giovaniceotto]

Pull request type

Please check the type of change your PR introduces:

• Code base additions (bugfix, features)
• Code maintenance (refactoring, formatting, renaming, tests)
• ReadMe, Docs and GitHub maintenance
• Other (please describe):

Pull request checklist

Please check if your PR fulfills the following requirements, depending on the type of PR:

• Code base additions (for bug fixes / features):

  • Tests for the changes have been added
  • Docs have been reviewed and added / updated if needed
  • Lint (black rocketpy) has passed locally and any fixes were made
  • All tests (pytest --runslow) have passed locally

What is the current behavior?

See #205, #251 and #261.

What is the new behavior?

• Issue ModuleNotFoundError: No module named 'ipywidgets' #251 has been fixed.
• Issue SyntaxError: current version fails to run on Python releases earlier than 3.8 #261 has been fixed.
• GitHub actions has been update to run tests using Python 3.7, which is used in Google Colab.
• netCDF4 requirement version now needs to be below 1.6.0 to temporarily solve RuntimeError: Unable to load latest weather data for GFS #205.

Does this introduce a breaking change?

• Yes
• No

Other information

See Colab at: https://colab.research.google.com/drive/1viSLeMVux1aaxqRhXTQ6Ubid7qG0-wUi?usp=sharing

[giovaniceotto]

@MrGribel, I am a bit worried about the new verison requirement for netCDF4. What do you think happens if someone has a version above 1.6.0 and tries to update rocketpy?

[MrGribel]

Congrats on the fast response @giovaniceotto

Addressing your question, I've had netCDF4-1.6.1 installed on my local machine, and pip uninstalled it before installing the older netCDF4-1.5.8 when given the new requirements file, which I assume the behavior you intended.

It worries me a bit that we are introducing a dependency on an older version of a package though (I've had experiences with these getting removed at times from PyPI, for example). I believe a better long term fix would be to figure out what's going on inside the netCDF4 library. Perhaps keep the issue #205 open for the time being.

Besides that, the rest of the changes seem like pretty straightforward fixes. Thanks for that!

[Gui-FernandesBR]

Thank you again, sir!