fix: Color/Name::from_str()` won't panic when encountering unicode values.

Previously it would try to byte-index a presumed ascii string to convert
hex to RGB, which could panic if the string wasn't actually ascii.

Now it validates that the characters to convert are actually on a character
boundary.

Author: Byron

gix-config-value/src/color.rs

@@ -204,7 +204,7 @@ impl FromStr for Name {
         }
 
         if let Some(s) = s.strip_prefix('#') {
-            if s.len() == 6 {
+            if s.len() == 6 && s.is_char_boundary(2) && s.is_char_boundary(4) && s.is_char_boundary(6) {
                 let rgb = (
                     u8::from_str_radix(&s[..2], 16),
                     u8::from_str_radix(&s[2..4], 16),

gix-config-value/tests/value/color.rs

@@ -54,6 +54,7 @@ mod name {
         assert!(Name::from_str("#").is_err());
         assert!(Name::from_str("#fff").is_err());
         assert!(Name::from_str("#gggggg").is_err());
+        assert!(Name::from_str("#=»©=").is_err());
     }
 }