Replace q with just q95

[chris-ashe]

Description

An update to #321 after merge.
q is now be in the input file as just q95

Using q95 makes it more explicit than just using q for the edge and the first assignment in physics() was to set q95 = q

 physics_variables.q95 = physics_variables.q

        # Calculate plasma composition
        # Issue #261 Remove old radiation model (imprad_model=0)
        self.plasma_composition()

Checklist

I confirm that I have completed the following checks:

• 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

All modified and coverable lines are covered by tests ✅

Project coverage is 31.55%. Comparing base (d2883c4) to head (af97a73).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3108   +/-   ##
=======================================
  Coverage   31.54%   31.55%           
=======================================
  Files          82       82           
  Lines       19567    19565    -2     
=======================================
  Hits         6173     6173           
+ Misses      13394    13392    -2     

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[timothy-nunn]

Two minor style points

[timothy-nunn]

Need to fix https://github.com/ukaea/PROCESS/actions/runs/13387816299/job/37388520836?pr=3502#step:7:1967 otherwise good to go

[timothy-nunn]

LGTM