Prevent ConstructorError when parsing YAML containing '=' scalars

[juergenhoetzel]

pyyaml assignes '=' to tag:yaml.org,2002:value even though there's no constructor for it. Removing the implicit resolver for '=' fixes the issue.

What type of PR is this?

/kind bug

What this PR does / why we need it:

Currently applying YAML documents containing the = scalar results in an error. Minimal example:

apiVersion: v1
kind: ConfigMap
metadata:
  name: demo
data:
  equal: =

from kubernetes import client, config, utils


def main():
    config.load_kube_config()
    k8s_client = client.ApiClient()
    yaml_file = "configmap.yml"
    utils.create_from_yaml(k8s_client, yaml_file, verbose=True)


if __name__ == "__main__":
    main()

results in:

yaml.constructor.ConstructorError: could not determine a constructor for the tag 'tag:yaml.org,2002:value'
  in "/home/juergen/ghq/github.com/kubernetes-client/python/configmap.yml", line 6, column 10

While the above example is contrived, this issue also hit me in real world when parsing the Prometheus operator CRD

NONE

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[roycaihw]

/assign @yliaog

[yliaog]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: juergenhoetzel, yliaog

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