chore(deps): bump skopeo/stable from v1.17.0 to v1.18.0 in /tests in the docker-tests group (#7436)

Author: dependabot[bot]

tests/Dockerfile

@@ -3,7 +3,7 @@
 FROM kindest/node:v1.32.2@sha256:f226345927d7e348497136874b6d207e0b32cc52154ad8323129352923a3142f
 
 # this is here so we can grab the latest version of skopeo and have dependabot keep it up to date
-FROM quay.io/skopeo/stable:v1.17.0
+FROM quay.io/skopeo/stable:v1.18.0
 
 FROM python:3.13@sha256:08471c63c5fdf2644adc142a7fa8d0290eb405cda14c473fbe5b4cd0933af601