modify model/base.py to fix issue #1228

[ebjordi]

Description

• Modified function Radial1DModel.from_csvy() so the dataframes are read appropriately, and that the first is removed only when it's being read from a csv table.

Motivation and Context

See #1235 and #1228 for context

How Has This Been Tested?

pytest passes for all test in the folder.
xfail tests will be added in the next PR of the project

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Add new tests

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have assigned/requested two reviewers for this pull request.

[codecov]

Codecov Report

Merging #1240 into master will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1240      +/-   ##
==========================================
- Coverage   80.63%   80.57%   -0.07%     
==========================================
  Files          41       41              
  Lines        3424     3428       +4     
==========================================
+ Hits         2761     2762       +1     
- Misses        663      666       +3     

Impacted Files	Coverage Δ
tardis/model/base.py	88.29% <100.00%> (-0.92%)	⬇️

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