chore: bump version to v1.20.0 for release

chore: bump version to v1.19.0 for release

chore: set version to v1.18.0 for release

chore: bump version to v1.17.0 for release

chore: bump version to v1.16.0 for release

chore: update version to v1.15.0 for release

fix(snap): temporarily remove go generate step to "fix" snap version

chore: change version to v1.14.0 for release

chore: update version to v1.13.0 for release

chore: update golang.org/x dependencies (canonical#426)

The update to x/net also fixes security issue
https://pkg.go.dev/vuln/GO-2024-2687 -- which doesn't actually affect
Pebble at the moment, but it's good to be up to date on these.