package/python-msgpack: fix project url

The previous url pointed to an unrelated but similarly named project.

Signed-off-by: Marcus Hoffmann <buildroot@bubu1.eu>
Signed-off-by: Julien Olivain <ju.o@free.fr>

package/python-msgpack/Config.in

@@ -6,4 +6,4 @@ config BR2_PACKAGE_PYTHON_MSGPACK
 	  This package provides a pure python library for reading
 	  and writing MessagePack data.
 
-	  https://pypi.python.org/pypi/msgpack-python/
+	  https://pypi.org/project/msgpack/