syntax: python: colorize decorators specially

Decorators are documented at https://peps.python.org/pep-0318/.

Signed-off-by: Matteo Raso <matteo_luigi_raso@protonmail.com>
Signed-off-by: Benno Schulenberg <bensberg@telfort.nl>

syntax/python.nanorc

@@ -24,6 +24,9 @@ color brightcyan "\<(exec|print)([[:blank:]]|$)"
 # Special values.
 color brightmagenta "\<(False|None|True)\>"
 
+# Decorators.
+color cyan "@[[:alpha:]_][[:alnum:]_.]*"
+
 # Mono-quoted strings.
 color brightgreen "'([^'\]|\\.)*'|"([^"\]|\\.)*"|'''|""""
 color normal "'''|""""