Bump winit from 0.20.0-alpha6 to 0.20.0

Bumps [winit](https://github.com/rust-windowing/winit) from 0.20.0-alpha6 to 0.20.0.
- [Release notes](https://github.com/rust-windowing/winit/releases)
- [Changelog](https://github.com/rust-windowing/winit/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-windowing/winit/commits)

Signed-off-by: dependabot-preview[bot] <[email protected]>

Author: dependabot-preview[bot]

Cargo.lock

@@ -52,7 +52,7 @@ reqwest = { version = "0.10.0", features = [ "blocking" ]}
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 stdweb = "0.4.20"
-winit = { version = "=0.20.0-alpha6", features = [ "stdweb" ]}
+winit = { version = "=0.20.0", features = [ "stdweb" ]}
 
 [dependencies.steven_gl]
 path = "./gl"