fix README.j2 recent change to MRSV 1.67

Author: jayvdb

README.j2

@@ -25,8 +25,8 @@
     <a href="https://www.rust-lang.org/en-US/">
         <img src="https://img.shields.io/badge/Made%20with-Rust-orange.svg" alt='Build with Rust' />
     </a>
-    <a href="https://blog.rust-lang.org/2022/11/03/Rust-1.67.0.html">
-        <img src="https://img.shields.io/badge/rustc-1.67+-yellow.svg" alt='Minimum Rust Version: 1.67' />
+    <a href="https://blog.rust-lang.org/2022/11/03/Rust-1.65.0.html">
+        <img src="https://img.shields.io/badge/rustc-1.65+-yellow.svg" alt='Minimum Rust Version: 1.65' />
     </a>
 </p>