use dh-sequence-python3

debian/control

@@ -7,7 +7,7 @@ Standards-Version: 4.6.2
 Rules-Requires-Root: no
 Homepage: https://github.com/fabiocaccamo/django-colorfield
 Build-Depends: debhelper-compat (= 13),
-               dh-python,
+               dh-sequence-python3,
                python3,
                python3-django,
                python3-djangorestframework <!nocheck>,

debian/rules

@@ -3,7 +3,7 @@
 export PYBUILD_NAME=django-colorfield
 
 %:
-	dh $@ --with python3 --buildsystem=pybuild
+	dh $@ --buildsystem=pybuild
 
 override_dh_auto_clean:
 	rm -f colorfield/static/jscolor/jscolor.min.js