remove spice dependency from tests for updated lunarsky

[aelanman]

Description

The latest version of lunarsky drops the dependency on spiceypy. As a result, the try blocks that catch SPICEUnknownFrameErrors in unit tests can be removed. This also bumps the minimum version of lunarsky.

Motivation and Context

This cleans up code that will no longer be needed.

Build or continuous integration change checklist:

• If required or optional dependencies have changed (including version numbers), I have updated the readme to reflect this.
• If this is a new CI setup, I have added the associated badge to the readme and to references/make_index.py (if appropriate).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.30%. Comparing base (69fd4ae) to head (c692ee2).

Additional details and impacted files

@@             Coverage Diff             @@
##              main     #620      +/-   ##
===========================================
- Coverage   100.00%   97.30%   -2.70%     
===========================================
  Files           11       11              
  Lines         2453     2453              
===========================================
- Hits          2453     2387      -66     
- Misses           0       66      +66     

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