install all the needed deps in the testing workflow

[cloudymax]

needs:

• minio
• cert-manager
• cnpg-operator

[jessebot]

cert-manager and cnpg-operator were done in #14 :) forgot minio 🤦

[cloudymax]

note to self for testing backups: https://github.com/small-hack/argocd-apps/tree/main/postgres/operators/cloud-native-postgres/backups