Time to mark this repository as deprecated/archived?

### Which service(blob, file, queue) does this issue concern?
All services.

### Which version of the SDK was used? Please provide the output of `pip freeze`.
N/A

### What problem was encountered?
It looks like this repository is stale; all new changes have been introduced to the 12.x branch which has been integrated to the main https://github.com/Azure/azure-sdk-for-python repository. No changes have been committed to this repository since December 2019.

### Have you found a mitigation/solution?
Please add a prominent migration notice, and archive this repository, if it is indeed deprecated.