Change CRDS keyword names.

[schlafly]

This updates the names of the keywords used to specify the CRDS software version and context used in romanisim.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.

Project coverage is 91.00%. Comparing base (81028a8) to head (afabb87).
Report is 15 commits behind head on main.

Files with missing lines	Patch %	Lines
romanisim/image.py	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #172      +/-   ##
==========================================
+ Coverage   89.24%   91.00%   +1.76%     
==========================================
  Files          17       16       -1     
  Lines        2073     2102      +29     
==========================================
+ Hits         1850     1913      +63     
+ Misses        223      189      -34     

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[schlafly]

Tests are passing and this is pretty simple; going ahead and merging.