Upgrade OpenModelica

[vtnate]

Any background context you want to provide?

A new version of OpenModelica was recently released. We can now take advantage of their "many improvements and bug fixes" in this newest version.

What does this PR accomplish?

• Update Dockerfile to use new OM version
  • Rename a variable in the Dockerfile
  • Move cmake to a different part of the Dockerfile to be as similar as possible to the OM Dockerfile ours is modeled on
• Declare new version of the Dockerfile in the Modelica readme
• Refer to the not-yet-created/uploaded Docker image in modelica_runner.py

How should this be manually tested?

• Generate new Docker image according to the docs
  • Tag it 2.1.03.0.0 (@nllong is that the right version for this change?)
• Upload to NREL's dockerhub account
• Run test suite
  • These tests are the ones that work with Ubuntu 20 but not with 22 or 24 😢 (due to something in this file that LBNL isn't interested in addressing) and make a good canary in the coal mine.

What are the relevant tickets?

Screenshots (if appropriate)

[nllong]

tests failing? should I wait until that gets resolved to review?

[vtnate]

tests failing? should I wait until that gets resolved to review?

No, please review now. The tests are failing because in modelica_runner.py I'm referring to an image that doesn't exist yet.

Will you please:

1. confirm that version 2.1.0 is correct
2. build the image
3. run the tests locally (if you don't trust me 😆)
4. push the image to dockerhub

Once those are good, I can re-run CI and once we have all green you can approve and we can merge it.