Fix missing quote in helm chart templates

[mymmrac]

Fixes missing quote on custom labels, in some places this was already present, but in charts/actions-runner-controller/templates/_helpers.tpl it was missing preventing values like "false" to be actually inserted into final YAML

After adding this fix, helm values like this should start working:

labels:
  test: "false"

Previously it was failing with an error:

unable to decode "": json: cannot unmarshal bool into Go struct field ObjectMeta.metadata.labels of type string