spelling of property heightPercentage in WaveWidget is written wrong as "heightPercentange"

[Lakshay]

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Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Version [e.g. 0.0.6]

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[RockerFlower]

64c559d
This PR has been merged, but since I am currently unable to log into pub.dev - (I believe it can be solved soon!), I am unable to release the update.