chore: fix deprecated exports syntax

[danielroe]

• note both fix: when using Node 16 will report an error #187 and Fix deprecated folder mapping: (node:5173) [DEP0148] #188 preceded this PR - would recommend merging one of them but opened this to document that the new syntax requires upgraded version of siroc

https://nodejs.org/api/packages.html#packages_subpath_folder_mappings

[codecov]

Codecov Report

Merging #189 (1cb9b43) into main (bcb8cd8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main     #189   +/-   ##
=======================================
  Coverage   86.04%   86.04%           
=======================================
  Files           7        7           
  Lines         172      172           
  Branches       45       45           
=======================================
  Hits          148      148           
  Misses         24       24           

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