Improve the jax example

[jhelgert]

Fixes #144 and #145 .

[moorepants]

The tests fail on macosx only with python 3.9, giving:

Installed /usr/local/miniconda/envs/test-environment/lib/python3.9/site-packages/cyipopt-1.2.0.dev0-py3.9-macosx-10.9-x86_64.egg
Processing dependencies for cyipopt==1.2.0.dev0
Searching for cyipopt==1.2.0.dev0
Reading https://pypi.org/simple/cyipopt/
/usr/local/miniconda/envs/test-environment/lib/python3.9/site-packages/pkg_resources/__init__.py:122: PkgResourcesDeprecationWarning:  is an invalid version and will not be supported in a future release
  warnings.warn(
No local packages or working download links found for cyipopt==1.2.0.dev0
error: Could not find suitable distribution for Requirement.parse('cyipopt==1.2.0.dev0')
Error: Process completed with exit code 1.

[moorepants]

This issue only being on Python 3.9 and Mac is odd:

Processing dependencies for cyipopt==1.2.0.dev0
Searching for cyipopt==1.2.0.dev0
Reading https://pypi.org/simple/cyipopt/
/usr/local/miniconda/envs/test-environment/lib/python3.9/site-packages/pkg_resources/__init__.py:122: PkgResourcesDeprecationWarning:  is an invalid version and will not be supported in a future release
  warnings.warn(
No local packages or working download links found for cyipopt==1.2.0.dev0
error: Could not find suitable distribution for Requirement.parse('cyipopt==1.2.0.dev0')
Error: Process completed with exit code 1.

It is like it is searching pypi for a cyipopt==1.20.dev0 to download. Not quite sure why it would be doing that. It thinks cyipopt is a dependency of itself.

[brocksam]

Our CI workflows is using python setup.py install to install CyIpopt. I think this is a hangover from distutils and might now be deprecated. I wonder if using pip install . instead might fix the weird macOS-only bug?

[moorepants]

Oh me, if they remove setup.py that's going to bring back Py2->Py3-like pains.

We can try the pip command instead for this.

[moorepants]

@jhelgert Can you merge in master to get this #149?

[jhelgert]

@moorepants Done.

[moorepants]

LGTM!

Thanks :)