Bump asyncpg to >=0.32.0: a server FATAL mid-transaction leaks a pool holder (#2540 part 1) - #2542

Part 1 of #2540 only. Do not merge without review. Parts 2 (the wake_workflow idle-in-txn holder) and 3 (the watchdog _task_for_connection frame walk) are NOT in this PR.

Mechanism (verified in the asyncpg 0.31.0 and 0.32.0 sdists)

• An idle-in-transaction FATAL arrives while the protocol is idle, so _read_server_messages hits unexpected state and sets PROTOCOL_ERROR_CONSUME (2).
• The next statement fails _set_state(15) with cannot switch to state 15; another operation (2) is in progress, which is the prod fingerprint. That calls _coreproto_error() → abort(), which sets closing=True.
• _on_connection_lost then takes the closing branch and skips con._cleanup(). In 0.31.0, PoolConnectionHolder.release() returns early on is_closed(), so the holder stays _in_use (in_use 1, idle == size).
• In 0.32.0 (Fix connection pool deadlock MagicStack/asyncpg#1324, 4a83cc2f), release() calls self._con.terminate() on a closed connection. That runs _cleanup() → _release_on_close() and re-queues the holder.

Red/green

tests/integration/test_pool_server_fatal_releases_holder.py builds the pool with aios create_pool, runs SET LOCAL idle_in_transaction_session_timeout='200ms' in a txn, sleeps 0.6s, then runs SELECT 1. It asserts in_use==0 and that max_size acquires succeed within 5s.

• asyncpg 0.31.0: FAILED holder leaked: in_use=1 size=1 idle=1, and the follow-up acquire times out.
• asyncpg 0.32.0: passed (5 of 5 runs).

The test routes through a local TCP relay that delays forwarding the server's close by 1s. Over loopback the FIN arrives in the same read as the FATAL, so connection_lost runs first, cleanup happens, and nothing leaks (verified: a direct connection does not reproduce the leak on 0.31.0). In prod the next query is sent before the FIN is seen.

Breaking-change review (0.32.0 changelog)

• Pool min_size semantics: it is now a maintained floor, refilled in the background, and new init_size defaults to min_size. aios uses min_size=1 by default, so the pool now reconnects one idle connection in the background after it dies instead of draining to 0. That is harmless. max_inactive_connection_lifetime no longer closes connections at or below min_size.
• SSL: direct TLS now requires sslmode=require/verify-*, and asyncpg sets ALPN postgresql on its own contexts. aios passes no ssl args or sslmode in code, so whether this matters depends on the prod DSN (not checked).
• Codecs: only new OIDs (oid8, regdatabase). No change to set_type_codec or the jsonb path.
• Python: requires_python >=3.9 is unchanged, and a cp313 manylinux wheel is in the lock.
• server_settings / init: no change to connect_utils handling.

uv.lock was regenerated with uv 0.11.0 so the lock stays at revision = 3 and the diff touches asyncpg only. A newer uv bumps it to revision 5, and the Dockerfile's uv 0.5.18 rewrites the whole file.