fix: fromWei and toWei typings

[joshstevens19]

Description

DefinitelyTyped/DefinitelyTyped#32409
DefinitelyTyped/DefinitelyTyped#32416
DefinitelyTyped/DefinitelyTyped#27528

Fix to fromWei and toWei typings

Type of change

• Bug fix
• New feature
• Breaking change

Checklist:

• I have selected the correct base branch.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have made corresponding changes to the documentation.
• My changes generate no warnings.
• I have updated or added types for all modules I've changed
• Any dependent changes have been merged and published in downstream modules.
• I ran npm run test in the root folder with success and extended the tests if necessary.
• I ran npm run build in the root folder and tested it in the browser and with node.
• I ran npm run dtslint in the root folder and tested that all my types are correct
• I have tested my code on the live network.

[coveralls]

Coverage remained the same at 92.704% when pulling 2b01bf5 on joshstevens19:fix/types/web3-utils into 599c52e on ethereum:1.0.

[coveralls]

Coverage remained the same at 92.704% when pulling 4affdb3 on joshstevens19:fix/types/web3-utils into 2cfa2ea on ethereum:1.0.