Remove alter function set_updated_at() owner to postgres;

[JWDobken]

This removes the explicit ownership change on set_updated_at().

This line assumes the existence of user postgres (which does not in my case). It will be owned by the user that creates it and that is fine.

What kind of change does this PR introduce?

Bug fix

What is the current behavior?

If not user postgres but another database user, you run into problems when the database user is explicitly named:

{"type":"Error","message":"Migration failed. Reason: An error occurred
 running 'add_updated_at'. Rolled back this migration. No further migrations were run. Reason: must be able to SET ROLE \"postgres\"","stack":"Error: Migration failed. Reason: An error
 occurred running 'add_updated_at'. Rolled back this migration. No further migrations were run. Reason: must be able to SET ROLE \"postgres\"\n    at /app/node_modules/.pnpm/pg-node-mi
grations@0.0.8/node_modules/pg-node-migrations/dist/migrate.js:108:27\n    at process.processTicksAndRejections (node:internal/process/task_queues:103:5)\n    at async /app/node_module
s/.pnpm/pg-node-migrations@0.0.8/node_modules/pg-node-migrations/dist/with-lock.js:25:28\n    at async connectAndMigrate (/app/packages/sync-engine/dist/index.cjs:2191:5)\n    at async
 runMigrations (/app/packages/sync-engine/dist/index.cjs:2210:5)","cause":"An error occurred running 'add_updated_at'. Rolled back this migration. No further migrations were run. Reaso
n: must be able to SET ROLE \"postgres\""},"msg":"Error running migrations"}

What is the new behavior?

The function is now owned by the database user that creates it.

[kevcodez]

Migrations cannot be changed right now as that would lead to a different checksum, breaking existing deployments

Once #234 lands we can modify older migrations