Restrict httpx version to <1.0.0

Author: Kludex

pyproject.toml

@@ -26,7 +26,7 @@ classifiers = [
 ]
 dependencies = [
     "anyio>=4.9",
-    "httpx>=0.27.1",
+    "httpx>=0.27.1,<1.0.0",
     "httpx-sse>=0.4",
     "pydantic>=2.12.0",
     "starlette>=0.48.0; python_version >= '3.14'",