cat data/ann.json | jq ".metadata.annotations | to_entries | map(if .key | contains("label") then .value="kuku" else . end) " 
[
  {
    "key": "deployment.kubernetes.io/revision",
    "value": "1"
  },
  {
    "key": "machine.openshift.io/owned",
    "value": ""
  },
  {
    "key": "label1",
    "value": "kuku"
  },
  {
    "key": "label2",
    "value": "kuku"
  },
  {
    "key": "label3",
    "value": "kuku"
  }
]