fix: use stringdata for oauth2-proxy secret

oauth2-proxy/templates/secret.yaml

@@ -4,7 +4,7 @@ metadata:
   name: {{ include "oauth2-proxy-helm.fullname" . }}
   labels:
     {{- include "oauth2-proxy-helm.labels" . | nindent 4 }}
-data:
+stringData:
   client-id: "{{ .Values.oidc.clientId }}"
   client-secret: "{{ .Values.oidc.clientSecret }}"
   cookie-secret: "{{ .Values.cookieSecret }}"