Remove trailing semicolon from err! macro

If the `semicolon_in_expressions_from_macros` lint is ever turned into a
hard error, your crate will stop compiling. This commit ensures that
your crate will compile on both current and future versions of Rust.

See rust-lang/rust#79813 for more details

src/lib.rs

@@ -1,6 +1,6 @@
 macro_rules! err {
     ($text:expr, $kind:expr) => {
-        return Err(Error::new($kind, $text));
+        return Err(Error::new($kind, $text))
     };
 
     ($text:expr) => {