fix(sticky-turbo): do not hard code path separator

[fuxingloh]

What this PR does / why we need it:

Do not hard code path separator and use sep from node:path.

Which issue(s) will this PR fix?:

Fixes #93

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[codecov]

Codecov Report

Merging #154 (d829eb3) into main (71d60a1) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #154   +/-   ##
=======================================
  Coverage   72.72%   72.72%           
=======================================
  Files           7        7           
  Lines         176      176           
  Branches       19       19           
=======================================
  Hits          128      128           
  Misses         45       45           
  Partials        3        3           

Impacted Files	Coverage Δ
packages/sticky-turbo/src/Turbo.ts	81.69% <100.00%> (ø)

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