fix: Fix a typo

Author: caoccao

hivemq-edge/src/main/java/com/hivemq/api/errors/ValidationError.java

@@ -27,7 +27,7 @@ public ValidationError(
             final @Nullable List<Error> errors) {
         super(
                 "ValidationError",
-                "Validatin failed",
+                "Validation failed",
                 "JSON failed validation.",
                 HttpStatus.BAD_REQUEST_400,
                 errors);