Remove violet release badge in favour of light blue

Violet got old fast.

Author: nhooyr

README.md

@@ -1,6 +1,6 @@
 # websocket
 
-[![GitHub release (latest SemVer)](https://img.shields.io/github/v/release/nhooyr/websocket?color=violet&sort=semver)](https://github.com/nhooyr/websocket/releases)
+[![GitHub release (latest SemVer)](https://img.shields.io/github/v/release/nhooyr/websocket?color=9cf&sort=semver)](https://github.com/nhooyr/websocket/releases)
 [![GoDoc](https://godoc.org/nhooyr.io/websocket?status.svg)](https://godoc.org/nhooyr.io/websocket)
 [![Codecov](https://img.shields.io/codecov/c/github/nhooyr/websocket.svg?color=brightgreen)](https://codecov.io/gh/nhooyr/websocket)
 [![CI](https://img.shields.io/circleci/build/github/nhooyr/websocket?label=ci&color=brightgreen)](https://github.com/nhooyr/websocket/commits/master)