Replace out-dated reqwest dependency

[dmfutcher]

New version of reqwest, v0.10 (https://github.com/seanmonstar/reqwest/releases/tag/v0.10.0), has breaking changes and will require code changes to use.

Not urgent but would like to keep up to date. Potential to help with #36.

[agersant]

Tangentially related to this issue. I noticed that because of its reliance on reqwest, rustfm-scrobble has quite a large dependency tree which pulls all sorts of crates from the async ecosystem.

This can be problematic for two sets of users:

• Users trying to keep their own dependencies minimal.
• Users with dependencies relying a different version of hyper. Not breaking per-se, but building TWO versions of hyper and friends can bloat builds a lot.

I am going to start working on a version of rustfm-scrobble using a more minimal (blocking) HTTP client like ureq. Which forms of this contribution would you be interested in?

A. As a full replacement for reqwest
B. Behind a feature-gate, keeping reqwest as the default
C. Not interested at all

Thanks!

Edit: I forgot to mention why I think there is little value in having this crate being part of the async ecosystem.

1. Async is useful to scale beyond a few hundred concurrent requests. Programs using rustfm-scrobble to make this many requests at the same time are most likely a very small niche, compared to programs who operate on behalf of a user.
2. Async frameworks have some form of block_on() method to handle long blocking operations without compromising their scheduling. This makes it possible to use synchronous code in an async context. But the opposite is not true: there is no working with async without tokio or async-std.

[dmfutcher]

Hey @agersant

Agree there's no need for async here. Happy to review a PR replacing reqwest entirely.

[dmfutcher]

Released in v1.1.0. Thanks for again for sorting this out @agersant!

[agersant]

Thanks!