fix(vault): use vault-secrets-provider's "latest" image tag

mentioned in commit 9adb2aab

mentioned in merge request to-be-continuous/samples/svelte-on-s3!118 (merged)

mentioned in merge request to-be-continuous/samples/mkdocs-on-s3!42 (merged)

mentioned in merge request to-be-continuous/samples/angular-on-s3!229 (merged)

mentioned in merge request to-be-continuous/samples/mkdocs-on-s3!52 (merged)