Fix utf-8 test when bstr v1.11 switchted to LowerHex

Author: khvzak

tests/string.rs

@@ -96,8 +96,8 @@ fn test_string_fmt_debug() -> Result<()> {
     assert_eq!(format!("{:?}", s.as_bytes()), "[104, 101, 108, 108, 111]");
 
     // Invalid utf8
-    let s = lua.create_string(b"hello\0world\r\n\t\xF0\x90\x80")?;
-    assert_eq!(format!("{s:?}"), r#"b"hello\0world\r\n\t\xF0\x90\x80""#);
+    let s = lua.create_string(b"hello\0world\r\n\t\xf0\x90\x80")?;
+    assert_eq!(format!("{s:?}"), r#"b"hello\0world\r\n\t\xf0\x90\x80""#);
 
     Ok(())
 }