Adds support for roman ramp data

[nden]

The Roman RampModel is missing meta.exposure.drop_frames1 and model.int_times.
This adds a check that those attributes exist before attempting to access them.

[codecov]

Codecov Report

Merging #43 (7246b23) into main (16036a2) will decrease coverage by 0.03%.
The diff coverage is 11.76%.

@@            Coverage Diff             @@
##             main      #43      +/-   ##
==========================================
- Coverage   40.88%   40.84%   -0.04%     
==========================================
  Files          14       14              
  Lines        2118     2120       +2     
==========================================
  Hits          866      866              
- Misses       1252     1254       +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	12.82% <13.33%> (-0.70%)	⬇️

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[kmacdonald-stsci]

Looks good.

[ddavis-stsci]

LGTM