Renamed tohsin to i_t_current_ramp_up

[j-a-foster]

Description

Renames tohsin to i_t_current_ramp_up to adhere to PROCESS standards.

---

Variables

• tohsin -> i_t_current_ramp_up: To match PROCESS style guide

Checklist

I confirm that I have completed the following checks:

• My changes follow the PROCESS style guide
• I have justified any large differences in the regression tests caused by this pull request in the comments.
• I have added new tests where appropriate for the changes I have made.
• If I have had to change any existing unit or integration tests, I have justified this change in the pull request comments.
• If I have made documentation changes, I have checked they render correctly.
• I have added documentation for my change, if appropriate.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 31.19%. Comparing base (6fc1dea) to head (2aabb3e).
⚠️ Report is 474 commits behind head on main.

Files with missing lines	Patch %	Lines
process/physics.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3558   +/-   ##
=======================================
  Coverage   31.19%   31.19%           
=======================================
  Files          83       83           
  Lines       19937    19936    -1     
=======================================
  Hits         6220     6220           
+ Misses      13717    13716    -1     

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[athoynilimanew]

Looks good to me. Anyone with merging permission can merge it now :)