Return version objects instead of mutating

version.py

@@ -36,10 +36,14 @@ class Version():
         return self.version_string
     
     def create_release_version(self):
-        if self.release_type == ReleaseType.PATCH:
-            self.is_snapshot = False
-        else:
-            self.increment()        
+        release_version = Version(self.version_list, self.release_type)
+        release_version.is_snapshot = self.is_snapshot
+        release_version.increment()
+        return release_version        
     
     def create_bump_version(self):
-        self.increment(ReleaseType.BUMP)
+        bump_version = Version(self.version_list, self.release_type)
+        bump_version.is_snapshot = self.is_snapshot
+        bump_version.release_type = ReleaseType.BUMP
+        bump_version.increment()
+        return bump_version