3.13.0 release
* add version 3.13 profile
* 3.13 end-of-life is 2022-11-01
* note we're an official Alpine project now!
* releases/alpine.yaml has been "--trim release"'d
* updated releases/README.md
scripts/builder.py
* fix ReleaseReadme() to not die when release contains "_rc"
* add --trim to releases-yaml
* tweak some --help for release-yaml and prune
scripts/setup-ami
* explicitly lock AMI root account
* switch build name from 'current-x86_64' to 'v#_#-x86_64' to avoid any confusion when new versions roll out
* resolvie-alpine.py.in - only warn about disabled regions once, instead of for each profile build
* make-amis - tweak script output
* new set of AMIs for edge, 3.10.0, and 3.9.4
* Build Profiles (completion of PR #49)
+ auto-updates version profile when new release detected
+ updates releases/<profile>.yaml after successful builds
* Prune AMIs (in AWS and in releases/<profile>.yaml
+ 'revision' - keep latest revision per release
+ 'release' - keep latest release per version
+ 'version' - remove end-of-life versions
* releases/README.md updater script
* README overhaul
+ Pre-built AMIs --> releases/README.md
+ profiles/README.md for profile configuration details
+ main README.md overhauled to go over how to build and manage custom AMIs
