תיקון בגניבה ב-2.53.0

תקציר מקורי באנגלית<h3>🛡️ Security</h3> <p>This release fixes one security issue in <code>ConcurrencyLimitedModel</code>. See the advisory for full details and affected versions.</p> <ul> <li><strong><a href="https://github.com/pydantic/pydantic-ai/security/advisories/GHSA-6fqq-452j-qhrp">GHSA-6fqq-452j-qhrp</a></strong> (high): a streamed request through <code>ConcurrencyLimitedModel</code> or <code>limit_model_concurrency</code> could keep its concurrency slot when the slot was released on a different task than the one that acquired it: after an early exit (the consumer stopped iterating, raised, or was cancelled), and also after fully consuming <code>stream_text()</code> with its default debouncing. Repeated streams could then block every request sharing the limiter. Agent-level <code>max_concurrency</co