Fix pyproject.toml

Author: RussellLuo

pyproject.toml

@@ -28,7 +28,7 @@ nats-py = "2.9.0"
 textual = "0.85.1"
 requests = "2.32.3"
 pygtrie = "2.5.0"
-httpx = "0.27.2"
+httpx = ">=0.28.0"
 h2 = "4.1.0"
 httpx-sse = "0.4.0"
 blinker = "1.9.0"
@@ -38,8 +38,15 @@ litellm = "1.60.4"
 mcp = ">=1.8.0"
 jinja2 = "3.1.5"
 
+# A list of optional dependencies, which are included in the
+# below `extras`.
+a2a-sdk = { version = ">=0.2.10", optional = true }
+starlette = { version = ">=0.47.0", optional = true }
+sse-starlette = { version = ">=2.3.6", optional = true }
+
+# Per https://python-poetry.org/docs/pyproject/#extras.
 [tool.poetry.extras]
-a2a = ["a2a-sdk>=0.2.10", "starlette>=0.47.0", "sse-starlette>=2.3.6"]
+a2a = ["a2a-sdk", "starlette", "sse-starlette"]
 
 [tool.pyright]
 # https://github.com/microsoft/pyright/blob/main/docs/configuration.md