* Add support for conditional requests with `ETag` and `Last-Modified`
* If a DynamoDB item exceeds the max size (400KB), skip writing to the cache and log a warning instead of raising an error
* Add `CachedResponse.closed` attribute for compatibility with `aiohttp.ClientResponse`
* Close `aiosqlite` thread if it's still running when session object is deleted
* Move redirects cache for `FileBackend` into same directory as cached response files
* Fix issue in which `CachedSession.disabled()` prevents only cache read but not write