fix: strip fluxcd managed labels

[jkroepke]

running helm diff against fluxcd managed helm release also shows a diff in terms of labels.

---

The current workaround is using

      --suppress-output-line-regex="helm.toolkit.fluxcd.io/name:" \
      --suppress-output-line-regex="helm.toolkit.fluxcd.io/namespace:" \

However, each single resource is present in the output with a suppressed notice.

An alternative approach would be:

      --strip-output-line-regex="helm.toolkit.fluxcd.io/name:" \
      --strip-output-line-regex="helm.toolkit.fluxcd.io/namespace:" \

The strip-output-lines is executed on source and target, before diff. Without any notice on the diff output.