package/python-dataproperty: drop python-six dependency

python-six is not a dependency since drop of python 2 in version 0.47.0:
https://github.com/thombashi/DataProperty/commit/d3fdde41af0151e2f04a3a79bea1fb33a28a98f7

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/python-dataproperty/Config.in

@@ -1,8 +1,7 @@
 config BR2_PACKAGE_PYTHON_DATAPROPERTY
 	bool "python-dataproperty"
-	depends on BR2_PACKAGE_PYTHON3 # python-mbstrdecoder
+	depends on BR2_PACKAGE_PYTHON3
 	select BR2_PACKAGE_PYTHON_MBSTRDECODER # runtime
-	select BR2_PACKAGE_PYTHON_SIX # runtime
 	select BR2_PACKAGE_PYTHON_TYPEPY # runtime
 	help
 	  Python library for extract property from data.