When updating a newly created mod:
```
Traceback (most recent call last):
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/lib/python3.8/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/lib/python3.8/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/KerbalStuff/common.py", line 81, in go
    ret = f(*args, **kwargs)
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/KerbalStuff/common.py", line 124, in wrapper
    result = f(*args, **kwargs)
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/KerbalStuff/blueprints/api.py", line 152, in wrapper
    return func(*args, **kwargs)
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/KerbalStuff/blueprints/api.py", line 738, in update_mod
    mod.score = get_mod_score(mod)
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/KerbalStuff/search.py", line 39, in get_mod_score
    num_incompat = versions_behind(mod)
  File "/var/www/virtual/spacedock.info/htdocs/SpaceDock/KerbalStuff/search.py", line 48, in versions_behind
    compat = version.Version(mod.default_version.gameversion.friendly_version)
AttributeError: 'NoneType' object has no attribute 'friendly_version'
```
So we should also call `db.commit()` before setting `mod.score` in `update_mod()`, same as `create_mod()`.