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>

tests/integration/agents/test_agents.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
+from typing import Any
 from uuid import uuid4
 
 import pytest
@@ -37,7 +37,7 @@ def get_boiling_point(liquid_name: str, celcius: bool = True) -> int:
         return -1
 
 
-def get_boiling_point_with_metadata(liquid_name: str, celcius: bool = True) -> Dict[str, Any]:
+def get_boiling_point_with_metadata(liquid_name: str, celcius: bool = True) -> dict[str, Any]:
     """
     Returns the boiling point of a liquid in Celcius or Fahrenheit
 

tests/integration/fixtures/recordable_mock.py

@@ -24,7 +24,7 @@ class RecordableMock:
         # Load existing cache if available and not recording
         if self.json_path.exists():
             try:
-                with open(self.json_path, "r") as f:
+                with open(self.json_path) as f:
                     self.cache = json.load(f)
             except Exception as e:
                 print(f"Error loading cache from {self.json_path}: {e}")

tests/integration/post_training/test_post_training.py

@@ -3,7 +3,6 @@
 #
 # This source code is licensed under the terms described in the LICENSE file in
 # the root directory of this source tree.
-from typing import List
 
 import pytest
 
@@ -77,7 +76,7 @@ class TestPostTraining:
     async def test_get_training_jobs(self, post_training_stack):
         post_training_impl = post_training_stack
         jobs_list = await post_training_impl.get_training_jobs()
-        assert isinstance(jobs_list, List)
+        assert isinstance(jobs_list, list)
         assert jobs_list[0].job_uuid == "1234"
 
     @pytest.mark.asyncio

tests/integration/test_cases/test_case.py

@@ -20,7 +20,7 @@ class TestCase:
         # loading all test cases
         if self._jsonblob == {}:
             for api in self._apis:
-                with open(pathlib.Path(__file__).parent / f"{api}.json", "r") as f:
+                with open(pathlib.Path(__file__).parent / f"{api}.json") as f:
                     coloned = api.replace("/", ":")
                     try:
                         loaded = json.load(f)