feat: support no_std (with mandatory alloc)

[polazarus]

No description provided.

[codecov]

Codecov Report

Merging #6 (69e0d05) into main (7aadff4) will increase coverage by 0.18%.
The diff coverage is 99.29%.

@@            Coverage Diff             @@
##             main       #6      +/-   ##
==========================================
+ Coverage   99.23%   99.42%   +0.18%     
==========================================
  Files          13       13              
  Lines        2621     2617       -4     
  Branches     2621     2617       -4     
==========================================
+ Hits         2601     2602       +1     
+ Misses         11        7       -4     
+ Partials        9        8       -1     

Files Changed	Coverage Δ
src/bytes/serde.rs	99.36% <ø> (ø)
src/raw.rs	100.00% <ø> (ø)
src/string/serde.rs	99.25% <ø> (ø)
src/backend.rs	99.01% <99.01%> (ø)
src/bytes.rs	99.69% <100.00%> (ø)
src/bytes/cmp.rs	100.00% <100.00%> (ø)
src/bytes/convert.rs	100.00% <100.00%> (ø)
src/raw/allocated.rs	100.00% <100.00%> (+4.31%)	⬆️
src/raw/inline.rs	95.06% <100.00%> (ø)
src/string.rs	99.56% <100.00%> (ø)
... and 2 more