add support for 3D arrays in JopInterp

[jkwashbourne-oss]

• Adds functionality for 3D arrays

[codecov]

Codecov Report

❌ Patch coverage is 92.77108% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.94%. Comparing base (b5518b7) to head (d7cceae).

Files with missing lines	Patch %	Lines
src/jop_interp.jl	92.77%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #45      +/-   ##
==========================================
- Coverage   96.02%   95.94%   -0.09%     
==========================================
  Files          40       40              
  Lines        1083     1159      +76     
==========================================
+ Hits         1040     1112      +72     
- Misses         43       47       +4     

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[jkwashbourne-oss]

Question, should we change this to JopLinearInterp ?

[nmbader]

Best to keep the same name to avoid bumping major version.
Speaking of which, remember to update Project.toml