fix(fetch): specify httpx<0.28 to resolve proxy problem

- AsyncClient.__init__() got an unexpected keyword argument 'proxies'

src/fetch/pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "mcp-server-fetch"
-version = "0.6.2"
+version = "0.6.3"
 description = "A Model Context Protocol server providing tools to fetch and convert web content for usage by LLMs"
 readme = "README.md"
 requires-python = ">=3.10"
@@ -16,6 +16,7 @@ classifiers = [
     "Programming Language :: Python :: 3.10",
 ]
 dependencies = [
+    "httpx<0.28",
     "markdownify>=0.13.1",
     "mcp>=1.1.3",
     "protego>=0.3.1",