Fix properly

Author: vidartf

pythreejs/_version.py

@@ -4,10 +4,10 @@
 
 postfix = ''
 if version_info[3] != 'final':
-    if version_info[3] == 'dev' and len(version_info) < 4:
+    if version_info[3] == 'dev' and len(version_info) < 5:
         postfix = 'dev0'
     else:
-        postfix = _specifier_[version_info[3]] + str(version_info[4]))
+        postfix = _specifier_[version_info[3]] + str(version_info[4])
 
 __version__ = '%s.%s.%s%s' % (version_info[0], version_info[1], version_info[2], postfix)