shader: adding gamma correction

[marsp0]

Small PR to add gamma correction to the shader. We were correcting the albedo texture incorrectly. Should be good now

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 8 lines in your changes missing coverage. Please review.

Project coverage is 67.39%. Comparing base (670b76a) to head (86189ea).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
src/math.c	66.66%	4 Missing ⚠️
src/shader.c	0.00%	4 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
- Coverage   67.61%   67.39%   -0.22%     
==========================================
  Files          20       20              
  Lines        1587     1592       +5     
  Branches      139      139              
==========================================
  Hits         1073     1073              
- Misses        506      511       +5     
  Partials        8        8              

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.