[server] Fix source component update
On component update the following exception was thrown:
```
a bytes-like object is required, not 'str'
```
We forgot to encode the component value when we moved to Python 3 so
this commit will solve this problem.
@@ -2362,7 +2362,7 @@ class ThriftRequestHandler(object):
user = self.__auth_session.user if self.__auth_session else None
if component:
- component.value = value
+ component.value = value.encode('utf-8')
component.description = description
component.user = user
else:
