In the `test_build` function, added support for the TEST_BUILD environment variable. Now, if the variable is set to True, the `test_build` function will run; otherwise, it will skip the test and output a related message. Additionally, introduced a new pytest fixture `if_test_build` to check if the test is enabled.
Added a `cookies` property accessor to the `BaseClient` class, which retrieves cookies from the `httpx` AsyncClient object and returns a `simnet.client.cookies.Cookies` object (which is a custom implementation of the `httpx.Cookies` class). Additionally, the initialization function was refactored to better support using cookies. Now, if `account_id` is not passed in, it will be retrieved from the cookies.