Fix service monitor matching labels

[cedvan]

Actually this template generate

  selector:
    app.kubernetes.io/instance: ovh-mks-exporter
    app.kubernetes.io/name: ovh-mks-exporter
    matchLabels: null

instead of

  selector:
    matchLabels:
      app.kubernetes.io/instance: ovh-mks-exporter
      app.kubernetes.io/name: ovh-mks-exporter

So deployment is break because crd not match correctly, this error is generated :
.spec.selector.app.kubernetes.io/instance: field not declared in schema

Just add missing indentation to fix

[rverchere]

Good catch, thanks!