Revert "Adds support for roman ramp data"

[nden]

Reverts #43

Broke jwst.
The attribute check should not be done in the RampClass methods only at the initial creation of the RampClass from a data model.

[codecov]

Codecov Report

Merging #48 (38bd305) into main (0373a76) will increase coverage by 0.03%.
The diff coverage is 13.33%.

@@            Coverage Diff             @@
##             main      #48      +/-   ##
==========================================
+ Coverage   37.73%   37.77%   +0.03%     
==========================================
  Files          14       14              
  Lines        2120     2118       -2     
==========================================
  Hits          800      800              
+ Misses       1320     1318       -2     

Impacted Files	Coverage Δ
src/stcal/ramp_fitting/ramp_fit.py	37.93% <0.00%> (ø)
src/stcal/ramp_fitting/ramp_fit_class.py	13.51% <15.38%> (+0.69%)	⬆️

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