[FIX] Add PDB support to latest kubernetes versions (#759)

Author: jenciso

charts/apisix/templates/pdb.yaml

@@ -15,7 +15,11 @@
 # limitations under the License.
 
 {{- if (.Values.podDisruptionBudget.enabled) }}
+{{ if semverCompare "<1.21-0" .Capabilities.KubeVersion.Version -}}
 apiVersion: policy/v1beta1
+{{- else -}}
+apiVersion: policy/v1
+{{- end }}
 kind: PodDisruptionBudget
 metadata:
   name: {{ include "apisix.fullname" . }}