[librsvg] Fix error message

[Federico Mena Quintero <federico src gnome org>]

commit 470042dc9c62d565b146ed5963a22b9627834a8a
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri Sep 14 08:28:47 2018 -0500

    Fix error message

 rsvg_internals/src/parsers.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/rsvg_internals/src/parsers.rs b/rsvg_internals/src/parsers.rs
index 4530331f..3333f72d 100644
--- a/rsvg_internals/src/parsers.rs
+++ b/rsvg_internals/src/parsers.rs
@@ -65,7 +65,7 @@ impl Parse for String {
         Ok(String::from(
             parser
                 .expect_string()
-                .map_err(|_| AttributeError::Parse(ParseError::new("expected number")))?
+                .map_err(|_| AttributeError::Parse(ParseError::new("expected string")))?
                 .as_ref(),
         ))
     }