update msrv badge

Author: mmalecot

README.md

@@ -3,7 +3,7 @@
 ![Build](https://img.shields.io/github/actions/workflow/status/mmalecot/file-format/ci.yml?branch=main&style=flat-square&logo=github)
 [![Crates.io](https://img.shields.io/crates/v/file-format.svg?style=flat-square)](https://crates.io/crates/file-format)
 [![Docs](https://img.shields.io/docsrs/file-format?style=flat-square&logo=docs.rs)](https://docs.rs/file-format)
-![Rust](https://img.shields.io/badge/rust-1.60+-blueviolet.svg?logo=rust&style=flat-square)
+![Rust](https://img.shields.io/badge/rust-1.85+-blueviolet.svg?logo=rust&style=flat-square)
 ![License](https://img.shields.io/badge/license-MIT%2FApache--2.0-blue.svg?style=flat-square)
 
 Crate for determining the file format of a given file or stream.