Update version

The problematic 1.2.0 couldn't be uploaded because it was already uploaded to PyPI.
See https://pypi.org/help/#file-name-reuse

Author: kozo2

setup.py

@@ -11,7 +11,7 @@
 
 setup(
     name='ecell4',
-    version='1.2.0',
+    version='1.2.1',
     packages=['ecell4', 'ecell4.util', 'ecell4.extra', 'ecell4.datasource', 'ecell4.mca', 'ecell4.plotting'],
     package_data = {"ecell4.util": [
         "templates/init_ipynb.js", "templates/init_cyjs.js", "templates/template.html",