Adding image check to pull request workflow and bumping scripts version

[lucasmlp]

• Adds a new step in the pull request workflow to check all the container images used in the project;
• The step will run only if the pull request is opened against a release branch;
• If the step fails, the workflow doesn't fail. The reason for this is that we have two tags from the fluent-bit repository that don't exist in Docker Hub. Until we figure that out, the new step would fail all the PRs if it was required to run successfully. After sorting the tags out we'll set the step success to be required;
• Fixes rancher-external-ip-webhook chart description that is breaking the validation script.