Hack octocatalog-diff script to support puppet 7

This applies the puppet 7 Puppetfile changes to both source and target branch before running octocatalog-diff.

While debugging this, I noticed that we hadn't updated the gitconfig used to override remote clones with local clones, so fix that (and add the missing puppet-kmod to the mrconfig).

Ref. swh/infra/sysadm-environment#4778

assigned to @olasd

It works ! Great !

cd puppet-environment
git fetch
git checkout mr/octocatalog-diff-puppet-7
mr update
cd swh-site
git checkout mr/puppet-7-compat
git checkout production
cd ..
bin/octocatalog-diff pergamon

approved this merge request

merged