Ruby 3.0+ Support

[aquaflamingo]

Howdy!

First off, awesome library! Been building a few projects with it, thanks for building this :)

It seems that RSpotify breaks with the move to Ruby 3, specifically it seems centered around the URI.encode method from the looks of this issue:
#236

Seems that the method has now been removed in higher version of Ruby, namely 3.0.

I see a few pull requests open that could help out
#228
#233

Wondering if it would be possible to get them merged. Happy to help out where possible to get these over the line if interested. Let me know, thanks again for the lib! :)

[aquaflamingo]

Whoops, disregard. Seems that the addressable gem has already been bumped to 2.8.0 in 94d0cc3.

So perhaps those PRs will not help.

[aquaflamingo]

Ah sincere apologies - this was total user error on my part. Closing !