Update get_input_var_names to return a list

[sverhoeven]

Change return type of get_input_var_names to list and convert the output.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 49.80%. Comparing base (d25431d) to head (728c1cb).
⚠️ Report is 4 commits behind head on main.

❗ There is a different number of reports uploaded between BASE (d25431d) and HEAD (728c1cb). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (d25431d)	HEAD (728c1cb)
	2	1

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #50       +/-   ##
===========================================
- Coverage   89.15%   49.80%   -39.35%     
===========================================
  Files          44        9       -35     
  Lines        2148      520     -1628     
  Branches        0       27       +27     
===========================================
- Hits         1915      259     -1656     
- Misses        233      258       +25     
- Partials        0        3        +3     

Components	Coverage Δ
Python	49.80% <50.00%> (∅)
Julia	∅ <ø> (∅)
R	∅ <ø> (∅)

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[BSchilperoort]

All good. Thanks for fixing