Use Locale.ROOT for signature byte conversion

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

Author: ianardee

src/main/java/com/mindee/parsing/BaseLocalResponse.java

@@ -158,7 +158,7 @@ public boolean isValidHmacSignature(String secretKey, String signature) {
       return false;
     }
     byte[] expectedBytes = getHmacSignature(secretKey).getBytes(StandardCharsets.UTF_8);
-    byte[] actualBytes = signature.toLowerCase().getBytes(StandardCharsets.UTF_8);
+byte[] actualBytes = signature.toLowerCase(java.util.Locale.ROOT).getBytes(StandardCharsets.UTF_8);
 
     return MessageDigest.isEqual(expectedBytes, actualBytes);
   }