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* FIX: SSH and SFTP support now works as expected in all types of kernels, including Alpine-based ones.
The auto-generated keypair name is changed to "id_container" and now it uses RSA instead of ECDSA for
better compatibility.
* FIX: Handle rarely happened ProcessLookupError when cleaning up kernels and stat synchronizers
which has caused infinitely repeated warning "cannot read stats: sysfs unreadable for container xxxx".
* FIX: Use the canonical, normalized version number for the backend.ai-common setup dependency to silence
pip warnings during installation.