Fix error message.

Fixes: #655

Author: basbossink-ds

src/error.rs

@@ -134,7 +134,7 @@ impl fmt::Display for Error {
             ErrorKind::Char {
                 character, index, ..
             } => {
-                write!(f, "invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-zA-Z], found `{}` at {}", character, index)
+                write!(f, "invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `{}` at {}", character, index)
             }
             ErrorKind::SimpleLength { len } => {
                 write!(

src/external/serde_support.rs

@@ -302,7 +302,7 @@ mod serde_tests {
     fn test_de_failure() {
         serde_test::assert_de_tokens_error::<Readable<Uuid>>(
             &[Token::Str("hello_world")],
-            "UUID parsing failed: invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-zA-Z], found `h` at 1",
+            "UUID parsing failed: invalid character: expected an optional prefix of `urn:uuid:` followed by [0-9a-fA-F-], found `h` at 1",
         );
 
         serde_test::assert_de_tokens_error::<Compact<Uuid>>(