Temporarily setting winning_score as nullable (#138)

<!--- Please write your PR name in the present imperative tense.
Examples of that tense are: "Fix issue in the dispatcher where…",
"Improve our handling of…", etc." -->
<!-- For more information on Pull Requests, you can reference here:
https://success.vanillaforums.com/kb/articles/228-using-pull-requests-to-contribute
-->
## Describe Your Changes

Temporarily setting `winning_score` as nullable

## Non-Obvious Technical Information


## Checklist Before Requesting a Review
- [x] The code runs successfully.

---------

Co-authored-by: Ari Anisfeld <ari.anisfeld@gmail.com>

prijateli_tree/migrations/versions/2024-01-07-0138_7a745e024c88_.py

@@ -16,7 +16,7 @@
 def upgrade():
     # ### commands auto generated by Alembic - please adjust! ###
     op.add_column(
-        "games", sa.Column("winning_score", sa.Integer(), nullable=False)
+        "games", sa.Column("winning_score", sa.Integer(), nullable=True)
     )
     # ### end Alembic commands ###