function "pkcs12cert" not defined for externsecrets in helm chart

I am trying to create tls secrets using Externalsecret and yaml file is created as below.

apiVersion: external-secrets.io/v1alpha1
kind: ExternalSecret
metadata:
  name: pgbouncer-serv
spec:
  refreshInterval: 5m
  secretStoreRef:
    kind: ClusterSecretStore
    name: env-secrets
  target:
    name: pgbouncer-serv
    creationPolicy: Owner
  template:
    type: kubernetes.io/tls
    engineVersion: v2
    data:
      tls.crt: "{{ .servsecret | pkcs12cert }}"
      tls.key: "{{ .servsecret | pkcs12key }}"
  data:
    - secretKey: servsecret
      remoteRef:
        key: SERV_CERT

we are trying create these external secrets in kubernetes cluster using helm chart, when i try to generate helm chart i am getting an error as function "pkcs12cert" not defined. can someone help me to rectify this error?