Merge branch 'ashmckenzie/use-bookworm-instead-of-bullseye' into 'main'

Upgrade to using bookworm instead of bullseye

See merge request https://gitlab.com/gitlab-org/gitlab-shell/-/merge_requests/956



Merged-by: Stan Hu <stanhu@gmail.com>
Approved-by: Stan Hu <stanhu@gmail.com>
Co-authored-by: Ash McKenzie <amckenzie@gitlab.com>

.gitlab-ci.yml

@@ -18,7 +18,7 @@ variables:
   BUNDLE_FROZEN: "true"
   GO_VERSION: "golang-1.21"
   GOPATH: $CI_PROJECT_DIR/.GOPATH
-  DEBIAN_VERSION: "bullseye"
+  DEBIAN_VERSION: "bookworm"
   RUBY_VERSION: "ruby-3.2"
   BUNDLE_PATH: vendor/ruby
   POLICY: pull