Allow Range prop step to be null in Typescript

[jnachtigall]

This is the same like #691 where it was fixed for Slider but Range seems to have been forgotten. Fixes #739 #652 #574

[vercel]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployment, click below or on the icon next to each commit.

🔍 Inspect: https://vercel.com/react-component/slider/4XiWdkNcS8zr3ueX3twniaUaKXpW
✅ Preview: https://slider-git-fork-jnachtigall-allowrangesteppropto-d28ee8.vercel.app

[codecov]

Codecov Report

Merging #757 (2ac1681) into master (b959281) will not change coverage.
The diff coverage is 100.00%.

❗ Current head 2ac1681 differs from pull request most recent head df0fe28. Consider uploading reports for the commit df0fe28 to get more accurate results

@@           Coverage Diff           @@
##           master     #757   +/-   ##
=======================================
  Coverage   88.49%   88.49%           
=======================================
  Files          11       11           
  Lines         756      756           
  Branches      199      198    -1     
=======================================
  Hits          669      669           
  Misses         87       87           

Impacted Files	Coverage Δ
src/Range.tsx	77.32% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update b959281...df0fe28. Read the comment docs.