BUG: SSUSI bug and function deprecation

[aburrell]

Description

Fixes a bug identified when running several years of SSUSI data that revealed the dimensions sometimes change. Also deprecated a function introduced to pysat from this package, partially addressing issue #169.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• Breaking change (fix or feature that would cause existing functionality
  to not work as expected)

How Has This Been Tested?

Added a unit test and also loaded a year of data (2010, one day at a time) for F16.

Test Configuration

• Operating system: OS X Big Sur
• Version number: Python 3.9
• Any details about your local setup that are relevant: Expand xarray dims when concatenating data pysat#1123

Checklist:

• Make sure you are merging into the develop (not main) branch
• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules
• Add a note to CHANGELOG.md, summarizing the changes
• Update zenodo.json file for new code contributors

[aburrell]

Failing due to issues addressed in #129, I believe.

[jklenzing]

Since SSUSI data has not yet been released, do we need to deprecate the code? The next release here will be after pysat 3.1.0 and have that as a minimum req.

[jklenzing]

Verified that dmsp ssusi / timed guvi not present in last released version. Deprecation not needed since these functions have not yet been released, unless we are being super thorough.

Merging develop back into this should fix the setup issues.

[aburrell]

Waiting on pysat/pysat#1116 and pysat/pysat#1123 before tests will pass.

[jklenzing]

Re-running with pysat 3.1.0, we get

 ValueError: coordinate 'Epoch' not present in all datasets.

for the timed saber data. This appears in the other pull too, so something probably changed with expand_dims. Or possibly there's another update I haven't seen yet

[jklenzing]

Found the bug, it was in issue with TIMED SABER revealed by the new exapnd_dims code. Out of scope here, working on a solution. Wrote up a summary in #174

[jklenzing]

Merging in the recent changes from develop should fix the errors