update setup version

setup.py

 import setuptools
-import csst_cpic_sim
 
 with open("requirements.txt", "r") as f:
     requirements = [
@@ -11,7 +10,7 @@ with open("requirements.txt", "r") as f:
 
 setuptools.setup(
     name='csst_cpic_sim',
-    version=csst_cpic_sim.__version__,
+    version='2.0.0',
     author='CSST Team',
     author_email='gzhao@niaot.ac.cn',
     description='The CSST CPIC Simulation',  # short description