Fix pushable type

[schoenwaldnils]

Fixes #654

[vercel]

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[codecov]

Codecov Report

Merging #713 (0e60adf) into master (a92703d) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #713   +/-   ##
=======================================
  Coverage   88.18%   88.18%           
=======================================
  Files          11       11           
  Lines         711      711           
  Branches      180      180           
=======================================
  Hits          627      627           
  Misses         84       84           

Impacted Files	Coverage Δ
src/Range.tsx	75.45% <ø> (ø)

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