Fix crates.io badge

Author: atouchet

README.md

@@ -1,7 +1,7 @@
 # unicode-security
 
 [![Build Status](https://github.com/unicode-rs/unicode-security/workflows/Tests/badge.svg)](https://github.com/unicode-rs/unicode-security/actions)
-[![Current Version](https://meritbadge.herokuapp.com/unicode-security)](https://crates.io/crates/unicode-security)
+[![Current Version](https://img.shields.io/crates/v/unicode-security.svg)](https://crates.io/crates/unicode-security)
 [![License: MIT/Apache-2.0](https://img.shields.io/crates/l/unicode-security.svg)](#license)
 
-This crate exposes various utilities from [UAX #39 Unicode Security Mechanisms](https://www.unicode.org/reports/tr39/)
+This crate exposes various utilities from [UAX #39 Unicode Security Mechanisms](https://www.unicode.org/reports/tr39/)