clang-tidy: use auto

[neheb]

Found with modernize-use-auto

Signed-off-by: Rosen Penev rosenp@gmail.com

[codecov]

Codecov Report

Merging #1711 (c01786d) into main (19000cd) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1711   +/-   ##
=======================================
  Coverage   66.89%   66.89%           
=======================================
  Files         151      151           
  Lines       20761    20761           
=======================================
  Hits        13889    13889           
  Misses       6872     6872           

Impacted Files	Coverage Δ
src/tags_int.hpp	90.90% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 19000cd...c01786d. Read the comment docs.