Gcp-storage-emulator

* Bumps Python to 3.9.5-slim

* Bumps Python from 3.9.2-slim to 3.9.3-slim

* Initial Python 3.10 support
* Enable env variables STORAGE_BASE and STORAGE_DIR
* Docker container stores data under /storage

* `alt=media` support 24
https://cloud.google.com/storage/docs/json_api/v1/objects/get
* `X-Goog-Hash` crc32c and md5 headers 22

* Added support: `start` and `end` download parameters

https://googleapis.dev/python/storage/latest/_modules/google/cloud/storage/blob.html#Blob.download_as_bytes

* Replace `crc32c` dependency with `google-crc32c`. It comes with a pure Python implementation that might work better in weird environments.