Rollup merge of #81571 - schteve:fix_e0759_typo, r=jonas-schievink

Fix typo in E0759

Minor typo in E0759 error message.

compiler/rustc_error_codes/src/error_codes/E0759.md

@@ -27,7 +27,7 @@ fn bar(x: &i32) -> Box<dyn Debug + 'static> { // ok!
 }
 ```
 
-Both [`dyn Trait`] and [`impl Trait`] in return types have a an implicit
+Both [`dyn Trait`] and [`impl Trait`] in return types have an implicit
 `'static` requirement, meaning that the value implementing them that is being
 returned has to be either a `'static` borrow or an owned value.