update-multitenant-dep: just tag everyone (#148)

### What

The `update-multitenant-dep` flow seems to fail:
```
GraphQL: Could not resolve to a User with the login of 'github-merge-queue[bot]'. (u000)
```

I think this is because we use merge queues, so when we assign the PR to
`$GITHUB_ACTOR` we actually assign it to `github-merge-queue[bot]`
instead of the developer.

### How

We'll assign it to the team.

.github/workflows/update-multitenant-dep.yaml

@@ -68,4 +68,4 @@ jobs:
             --title "dep update: update ndc-postgres to $LATEST_SHA" \
             --head "$BRANCH_NAME" \
             --base "main" \
-            --assignee "$GITHUB_ACTOR"
+            --reviewer "hasura/native-databases"