Fix error message about invalid surrogate pairs

I tested following strings with invalid surrogate pair and unpaired surrogate in files:

1. `"a\uD800\uD800x"`
2. `"a\uD800x"`

The error messge was: "... invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF; ..."

I think it must be: "... invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF; ..."

include/nlohmann/detail/input/lexer.hpp

@@ -338,13 +338,13 @@ class lexer
                                     }
                                     else
                                     {
-                                        error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
+                                        error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
                                         return token_type::parse_error;
                                     }
                                 }
                                 else
                                 {
-                                    error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
+                                    error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
                                     return token_type::parse_error;
                                 }
                             }

single_include/nlohmann/json.hpp

@@ -8201,13 +8201,13 @@ class lexer
                                     }
                                     else
                                     {
-                                        error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
+                                        error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
                                         return token_type::parse_error;
                                     }
                                 }
                                 else
                                 {
-                                    error_message = "invalid string: surrogate U+DC00..U+DFFF must be followed by U+DC00..U+DFFF";
+                                    error_message = "invalid string: surrogate U+D800..U+DBFF must be followed by U+DC00..U+DFFF";
                                     return token_type::parse_error;
                                 }
                             }