Getting `psycopg.OperationalError` constantly after a while on transactions

Describe the bug
I'm using FastAPI and TortoiseORM with psycopg to connect to a PostgreSQL database. It's been working great but after a while (2~3 days) I get constant psycopg.OperationalError: the connection is closed errors on every in_transaction()

To Reproduce
Basically just a async with in_transaction() block that gets constantly executed over a long period of time.

Expected behavior
For TortoiseORM to gracefully recover from connection errors if they happen on transactions.

Additional context
Using tortoise-orm[psycopg] version 0.25.1

Full traceback:

Traceback (most recent call last):
	...
  File "/app/client.py", line 84, in register_client
    async with in_transaction():
               ~~~~~~~~~~~~~~^^
  File "/app/.venv/lib/python3.13/site-packages/tortoise/backends/base/client.py", line 335, in __aenter__
    await self.client.savepoint()
  File "/app/.venv/lib/python3.13/site-packages/tortoise/backends/psycopg/client.py", line 230, in savepoint
    return await self.begin()
           ^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.13/site-packages/tortoise/backends/base_postgres/client.py", line 33, in _translate_exceptions
    return await self._translate_exceptions(func, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.13/site-packages/tortoise/backends/psycopg/client.py", line 180, in _translate_exceptions
    return await func(self, *args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.13/site-packages/tortoise/backends/psycopg/client.py", line 227, in begin
    await self._transaction.__aenter__()
  File "/usr/local/lib/python3.13/contextlib.py", line 214, in __aenter__
    return await anext(self.gen)
           ^^^^^^^^^^^^^^^^^^^^^
  File "/app/.venv/lib/python3.13/site-packages/psycopg/connection_async.py", line 360, in transaction
    async with tx:
               ^^
  File "/app/.venv/lib/python3.13/site-packages/psycopg/transaction.py", line 271, in __aenter__
    await self._conn.wait(self._enter_gen())
  File "/app/.venv/lib/python3.13/site-packages/psycopg/connection_async.py", line 487, in wait
    return await waiting.wait_async(gen, self.pgconn.socket, interval=interval)
                                         ^^^^^^^^^^^^^^^^^^
  File "psycopg_binary/pq/pgconn.pyx", line 205, in psycopg_binary.pq.PGconn.socket.__get__
  File "psycopg_binary/pq/pgconn.pyx", line 718, in psycopg_binary.pq._call_int
  File "psycopg_binary/pq/pgconn.pyx", line 698, in psycopg_binary.pq._ensure_pgconn
psycopg.OperationalError: the connection is closed 

Start with tortoise/backends/base/client.py and the PostgreSQL transaction paths shown in tortoise/backends/psycopg/client.py and tortoise/backends/base_postgres/client.py. Reproduce the long-running async in_transaction() case and trace how a closed connection reaches begin(). Done means transaction use recovers gracefully from the reported connection error, with coverage for the failure if the repository has relevant tests.