docs: add crates.io badge to README

Author: dodoflix

README.md

@@ -4,6 +4,7 @@
 
 [![CI](https://github.com/oxidized-mc/client-headless/actions/workflows/ci.yml/badge.svg)](https://github.com/oxidized-mc/client-headless/actions/workflows/ci.yml)
 [![License: MIT](https://img.shields.io/badge/license-MIT-blue.svg)](LICENSE)
+[![Crates.io](https://img.shields.io/crates/v/oxidized-client-headless.svg)](https://crates.io/crates/oxidized-client-headless)
 
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