fix /api/v1/rules value

[yeya24]

Signed-off-by: yeya24 yb532204897@gmail.com

• I added CHANGELOG entry for this change.
• Change is not relevant to the end user.

Changes

Ref: prometheus/prometheus#5582

Verification

curl localhost:10906/api/v1/rules | jq
{
  "status": "success",
  "data": {
    "groups": [
      {
        "name": "test-alert-group",
        "file": "valid.yaml",
        "rules": [
          {
            "name": "test",
            "query": "1",
            "duration": 0,
            "labels": {
              "key": "value"
            },
            "annotations": {
              "key": "value"
            },
            "alerts": [
              {
                "labels": {
                  "alertname": "test",
                  "key": "value"
                },
                "annotations": {
                  "key": "value"
                },
                "state": "firing",
                "activeAt": "2019-12-11T10:07:10.851171763-05:00",
                "value": "1e+00",
                "partial_response_strategy": "WARN"
              }
            ],
            "health": "ok",
            "type": "alerting",
            "partial_response_strategy": "WARN"
          }
        ],
        "interval": 5,
        "partial_response_strategy": "WARN"
      }
    ]
  }
}

[bwplotka]

Thanks!