dss_python==0.13.1 and set version to 0.8.1

Author: PMeira

opendssdirect/_version.py

@@ -1,2 +1,2 @@
 # -*- coding: utf-8 -*-
-__version__ = "0.8.0"
+__version__ = "0.8.1"

setup.py

@@ -46,7 +46,7 @@ def run(self):
     author_email="[email protected]",
     license="BSD-compatible",
     packages=find_packages(),
-    install_requires=["dss_python==0.13.0"],
+    install_requires=["dss_python==0.13.1"],
     extras_require={
         "extras": ["pandas", "matplotlib", "networkx"],
         "dev": [