Fixed ResourceWarnings in tests (#1366)

* #1320 Update pytest configuration and tests cleanup

This commit modifies the pytest's configuration file, `pyproject.toml`, to remove filterwarnings settings. It also makes changes in various test files; the Redis isolation test is now using the provided `redis_storage` fixture instead of setting up its own connection, pytest.mark.filterwarnings is no longer used in `test_isolation.py` and `test_aiohttp_session.py` properly closes off sessions.

* Added changelog

* Fixed coverage for the RedisEventIsolation

tests/conftest.py

@@ -38,7 +38,7 @@ def pytest_collection_modifyitems(config, items):
         raise UsageError(f"Invalid redis URI {redis_uri!r}: {e}")
 
 
-@pytest.fixture(scope="session")
+@pytest.fixture()
 def redis_server(request):
     redis_uri = request.config.getoption("--redis")
     return redis_uri
@@ -73,20 +73,9 @@ async def memory_storage():
 
 @pytest.fixture()
 @pytest.mark.redis
-async def redis_isolation(redis_server):
-    if not redis_server:
-        pytest.skip("Redis is not available here")
-    isolation = RedisEventIsolation.from_url(redis_server)
-    try:
-        await isolation.redis.info()
-    except ConnectionError as e:
-        pytest.skip(str(e))
-    try:
-        yield isolation
-    finally:
-        conn = await isolation.redis
-        await conn.flushdb()
-        await isolation.close()
+async def redis_isolation(redis_storage):
+    isolation = redis_storage.create_isolation()
+    return isolation
 
 
 @pytest.fixture()