syntax: default: colorize also two-digit and capitalized nano versions

syntax/default.nanorc

@@ -11,7 +11,7 @@ color cyan "^[[:space:]]*#.*"
 color ,red " +	+"
 
 # Nano's name, including version.
-color brightred "(GNU )?nano [1-9]\.[0-9]\.[^[:space:][:punct:]]+"
+color brightred "(GNU )?[Nn]ano [1-3]\.[0-9][-.[:alnum:]]*\>"
 
 # Email addresses.
 color magenta "<[[:alnum:].%_+-]+@[[:alnum:].-]+\.[[:alpha:]]{2,}>"