add support for automatically replacing quarterly versions of parent cimgs. this is generally meant to affect images built off of cimg/base and is defined in the manifest. some exceptions, like clojure build off something different
add support for changing parent versions of monthly releases like cimg/gcp, cimg/aws, cimg/azure, which are based off cimg-deploy
fixes a problem with sed creating a .bak file which we do not want to include as part of an automated PR
cimg/gcp,cimg/aws,cimg/azure, which are based off cimg-deploy