Fixed typo: about about

Removed a typo where the word _about_ was used twice: 
> The compiler will warn about `about` potentially confusing situations involving different scripts.

Author: JoelMon

posts/2021-06-17-Rust-1.53.0.md

@@ -103,7 +103,7 @@ struct 人 {
 let α = 1;
 ```
 
-The compiler will warn about about potentially confusing situations involving different scripts.
+The compiler will warn about potentially confusing situations involving different scripts.
 For example, using identifiers that look very similar will result in a warning.
 
 ```