Cleared compiler warnings except for Highs_compilationDate

[jajhall]

I don't understand why there is a compiler warning for

static const char* Highs_compilationDate(void);

in /home/jajhall/HiGHS/highs/interfaces/highs_c_api.cpp, but it's deprecated

Other compiler warnings cleared (except for those from cuPDLP-c)

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 80.32%. Comparing base (a058a69) to head (67d50c3).
⚠️ Report is 63 commits behind head on latest.

Files with missing lines	Patch %	Lines
highs/interfaces/highs_c_api.cpp	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           latest    #2771      +/-   ##
==========================================
- Coverage   80.32%   80.32%   -0.01%     
==========================================
  Files         348      348              
  Lines       86073    86095      +22     
==========================================
+ Hits        69141    69154      +13     
- Misses      16932    16941       +9     

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