Fix wrong package name in setup.py

Author: Reshief

setup.py

@@ -3,7 +3,7 @@
 exec(open("ddesolver/version.py").read())  # loads __version__
 
 setup(
-    name="deesolver",
+    name="ddesolver",
     version=__version__,
     author="Reshief",
     author_email='[email protected]',