Update to yew 0.20

[WorldSEnder]

This PR tracks the changes necessary to update to the eventual yew 0.20 release. Upgrades:

• Use #[hook] on hook integration
• Use Renderer and features = ["csr"] in the examples

Closes #87 Closes #90

[cryptoquick]

Heads-up, the code in this PR no longer compiles, it gives this error:

   Compiling stylist v0.10.0 (https://github.com/WorldSEnder/stylist.git?branch=hooks#839dcc83)
error: cannot find attribute `hook` in this scope
  --> /home/hunter/.cargo/git/checkouts/stylist-45475ec210f96b03/839dcc8/packages/stylist/src/yew/hooks/use_media_query.rs:12:3
   |
12 | #[hook]
   |   ^^^^

error: cannot find attribute `hook` in this scope
  --> /home/hunter/.cargo/git/checkouts/stylist-45475ec210f96b03/839dcc8/packages/stylist/src/yew/hooks/use_style.rs:25:3
   |
25 | #[hook]
   |   ^^^^

error: could not compile `stylist` due to 2 previous errors

Using yew master on rev 5355b65ff5f9747cbad801d4b337a5ac7a94d0f4.