Fix aws assume role session creation when deferrable

[gopidesupavan]

Updated _create_session_with_assume_role to return aiobotocore.session.AioSession if session requested with deferrable=True

Tested with example:

aws_assume_role_connection = {
"region_name": "us-east-1",
"role_arn": "arn:aws:iam::{ACCOUNT_ID}:role/TestRoleAirflow",
"assume_role_method": "assume_role"
}

with DAG(
    dag_id=DAG_ID,
    start_date=datetime(2021, 1, 1),
    schedule=None,
    catchup=False,
) as dag:
    bucket = "s3://environ-issues-fix-repo/"

    base = ObjectStoragePath(bucket, conn_id="aws_assume_role_connection")

    key = f"test/sample.json"


    @task
    def read_file(path: ObjectStoragePath) -> None:
        with path.open() as f:
            print(json.loads(f.read()))


    read_file(base / key)

Closes: #39970

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[gopidesupavan]

cc: @Taragolis