Accept string type as Provider arg

[wolovim]

What was wrong?

When instantiating Providers, URI strings appear to be a typical usage pattern, including in our own docs. mypy warns against this though:

w3 = Web3(Web3.HTTPProvider('https://127.0.0.1:8545'))
# or:
w3 = Web3(Web3.WebsocketProvider('ws://127.0.0.1:8546'))

# produces warning:
# Argument 1 has incompatible type "str"; expected "Optional[URI]"

How was it fixed?

URI -> Optional[Union[URI, str]]

Todo:

• Add entry to the release notes

Cute Animal Picture

[njgheorghita]

Nice! Yea, it doesn't feel like a fair requirement that users casts the string to URI before passing it into the provider - so this all checks out for me.

In retrospect, as the person who implemented a lot of the types in this library, it feels like a lot of these typing bugs/oversights are my fault, so apologies for any stress / time that you've been caused on my account/sloppiness. Definitely feel free to ping me if I can help with any issues.