ci: enable warnings as errors

[sergiud]

No description provided.

[codecov-commenter]

Codecov Report

Merging #759 (a6f022e) into master (660352f) will increase coverage by 0.15%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master     #759      +/-   ##
==========================================
+ Coverage   72.86%   73.02%   +0.15%     
==========================================
  Files          17       17              
  Lines        3225     3218       -7     
==========================================
  Hits         2350     2350              
+ Misses        875      868       -7     

Impacted Files	Coverage Δ
src/symbolize.cc	64.11% <0.00%> (+1.29%)	⬆️

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