Cloud-init SRU 21.3-1 released into Bionic, Focal, and Hirsute

Canonical has just finished Stable Release Update (SRU) validation of
cloud-init version 21.3-1 into Ubuntu Bionic, Focal, and Hirsute. It is
currently available in the -updates repositories and will
make it into certified cloud images in the next few days.

The changelog provided in this update can be seen in the package changelog
or in the following two process bugs:

Thank you all for your contributions to this version of cloud-init.