fixup! fix: unsoundness in NgxStr conversions

Author: bavshin-f5

src/core/string.rs

@@ -244,7 +244,7 @@ mod tests {
         let a: &NgxStr = "Hello World!".into();
 
         let s = "Hello World!".to_string();
-        let b: &NgxStr = NgxStr::from_bytes(s.as_bytes());
+        let b: &NgxStr = s.as_bytes().into();
 
         // The compiler should detect that s is borrowed and fail.
         // drop(s); // ☢️