Fixed line 45 SimpleStepper.js

[jossydeleon]

annoying message complaining about Annoying 'Invalid argument supplid to oneOfType' warning.
Line 45 was change to property oneOf instead of OneOfType

[codecov-commenter]

Codecov Report

Merging #33 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #33   +/-   ##
=======================================
  Coverage   90.90%   90.90%           
=======================================
  Files           5        5           
  Lines         110      110           
=======================================
  Hits          100      100           
  Misses         10       10           

Impacted Files	Coverage Δ
src/SimpleStepper.js	90.00% <ø> (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 d3f15cb...68ddceb. Read the comment docs.