Update version.py

Change version for 2.1.0

Author: arnaudbore

scilpy/version.py

@@ -8,7 +8,7 @@
 _version_major = 2
 _version_minor = 1
 _version_micro = 0
-_version_extra = 'rc1'
+_version_extra = ''
 
 # Construct full version string from these.
 _ver = [_version_major, _version_minor, _version_micro]