chore: enable pyupgrade fixes (#1806)

# What does this PR do?

The goal of this PR is code base modernization.

Schema reflection code needed a minor adjustment to handle UnionTypes
and collections.abc.AsyncIterator. (Both are preferred for latest Python
releases.)

Note to reviewers: almost all changes here are automatically generated
by pyupgrade. Some additional unused imports were cleaned up. The only
change worth of note can be found under `docs/openapi_generator` and
`llama_stack/strong_typing/schema.py` where reflection code was updated
to deal with "newer" types.

Signed-off-by: Ihar Hrachyshka <ihar.hrachyshka@gmail.com>

llama_stack/providers/remote/tool_runtime/wolfram_alpha/config.py

@@ -4,7 +4,7 @@
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
 
-from typing import Any, Dict, Optional
+from typing import Any
 
 from pydantic import BaseModel
 
@@ -12,10 +12,10 @@ from pydantic import BaseModel
 class WolframAlphaToolConfig(BaseModel):
     """Configuration for WolframAlpha Tool Runtime"""
 
-    api_key: Optional[str] = None
+    api_key: str | None = None
 
     @classmethod
-    def sample_run_config(cls, __distro_dir__: str, **kwargs: Any) -> Dict[str, Any]:
+    def sample_run_config(cls, __distro_dir__: str, **kwargs: Any) -> dict[str, Any]:
         return {
             "api_key": "${env.WOLFRAM_ALPHA_API_KEY:}",
         }

llama_stack/providers/remote/tool_runtime/wolfram_alpha/wolfram_alpha.py

@@ -5,7 +5,7 @@
 # the root directory of this source tree.
 
 import json
-from typing import Any, Dict, Optional
+from typing import Any
 
 import httpx
 
@@ -50,7 +50,7 @@ class WolframAlphaToolRuntimeImpl(ToolsProtocolPrivate, ToolRuntime, NeedsReques
         return provider_data.wolfram_alpha_api_key
 
     async def list_runtime_tools(
-        self, tool_group_id: Optional[str] = None, mcp_endpoint: Optional[URL] = None
+        self, tool_group_id: str | None = None, mcp_endpoint: URL | None = None
     ) -> ListToolDefsResponse:
         return ListToolDefsResponse(
             data=[
@@ -68,7 +68,7 @@ class WolframAlphaToolRuntimeImpl(ToolsProtocolPrivate, ToolRuntime, NeedsReques
             ]
         )
 
-    async def invoke_tool(self, tool_name: str, kwargs: Dict[str, Any]) -> ToolInvocationResult:
+    async def invoke_tool(self, tool_name: str, kwargs: dict[str, Any]) -> ToolInvocationResult:
         api_key = self._get_api_key()
         params = {
             "input": kwargs["query"],