fix: only fallback to ts-node when it's available

[JounQin]

close #128

[changeset-bot]

🦋 Changeset detected

Latest commit: 31139c5

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
synckit	Patch

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📊 Package size report   No changes

File	Before	After
Total (Includes all files)	43.5 kB	43.5 kB
Tarball size	11.7 kB	11.7 kB

Unchanged files

File	Size
lib/index.cjs	10.0 kB
lib/index.d.ts	1.4 kB
lib/index.js	9.8 kB
lib/index.js.map	9.0 kB
lib/types.d.ts	888 B
lib/types.js	44 B
lib/types.js.map	102 B
LICENSE	1.1 kB
package.json	3.4 kB
README.md	7.9 kB

_{🤖 This report was automatically generated by pkg-size-action}

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b7be102) 100.00% compared to head (31139c5) 100.00%.

Additional details and impacted files

@@            Coverage Diff            @@
##              main      #141   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            2         2           
  Lines          130       132    +2     
  Branches        57        58    +1     
=========================================
+ Hits           130       132    +2     

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