Replace deprecated std package's constants on floats and integers

[k-yomo]

We can use associated constants on floats and integers directly from rust 1.4.3, and imported constants are deprecated now.

This PR replaces those deprecated constants.

[codecov-commenter]

Codecov Report

Merging #1420 (d019506) into main (d24f31f) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main    #1420   +/-   ##
=======================================
  Coverage   94.21%   94.21%           
=======================================
  Files         236      236           
  Lines       43775    43775           
=======================================
+ Hits        41243    41244    +1     
+ Misses       2532     2531    -1     

Impacted Files	Coverage Δ
src/docset.rs	67.50% <ø> (ø)
src/indexer/index_writer.rs	96.82% <ø> (ø)
src/tokenizer/mod.rs	95.61% <ø> (ø)
common/src/lib.rs	89.33% <100.00%> (ø)
common/src/serialize.rs	89.80% <100.00%> (ø)
common/src/vint.rs	92.35% <100.00%> (ø)
query-grammar/src/query_grammar.rs	99.67% <100.00%> (ø)
src/fastfield/writer.rs	91.05% <100.00%> (ø)
src/fieldnorm/code.rs	100.00% <100.00%> (ø)
src/indexer/merger.rs	98.91% <100.00%> (ø)
... and 9 more

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[fulmicoton]

thank you