fix: pin httpx to <1.0 to prevent incompatible prerelease versions (#483)

httpx 1.0.dev3 has breaking API changes (TransportError removed/renamed)
that break httpx_sse compatibility. Users with --prerelease flag were
getting AttributeError on import.

Related to #450 which added httpx[socks] support.

Fixes: AttributeError: module 'httpx' has no attribute 'TransportError'

Author: julienld

pyproject.toml

@@ -25,7 +25,7 @@ classifiers = [
 
 dependencies = [
     "fastmcp>=2.11.0",
-    "httpx[socks]>=0.27.0",
+    "httpx[socks]>=0.27.0,<1.0",
     'jq>=1.8.0; sys_platform != "win32"',
     "pydantic>=2.5.0",
     "python-dotenv>=1.0.0",