Fix error in pypi pre-requisites

Author: kotfu

tasks.py

@@ -188,7 +188,7 @@ def build(context):
 namespace.add_task(build)
 
 
-@invoke.task(pre=build)
+@invoke.task(pre=[build])
 def pypi(context):
     "Build and upload a distribution to pypi"
     context.run("twine upload dist/*")
@@ -197,7 +197,7 @@ def pypi(context):
 namespace.add_task(pypi)
 
 
-@invoke.task(pre=build)
+@invoke.task(pre=[build])
 def pypi_test(context):
     "Build and upload a distribution to https://test.pypi.org"
     context.run("twine upload --repository-url https://test.pypi.org/legacy/ dist/*")