Exclude managedFields from diff

[jonnylangefeld]

Since kubernetes 1.18 the kube api server adds a managedFields object to created objects. This can be quite large for some objects and makes the diff unreadable. managedFields should be excluded from the diff

./bin/isopod --context cluster=kind-kind -kubeconfig=/tmp/kind-kubeconfig -dry_run install $(pwd)/local/testenv/main.ipd
Current cluster: ("kind-kind")

*** customresourcedefinition.apiextensions.k8s.io `crontabs.stable.example.com' ***
--- live
+++ head
@@ -5,90 +5,10 @@
   resourceVersion: "671"
   labels:
     heritage: isopod
   annotations:
     isopod.getcruise.com/context: '{"cluster":"kind-kind","env":"dev"}'
-  managedFields:
-  - manager: Go-http-client
-    operation: Update
-    apiVersion: apiextensions.k8s.io/v1beta1
-    time: "2020-05-22T17:45:33Z"
-    fieldsType: FieldsV1
-    fieldsV1:
-      f:metadata:
-        f:annotations:
-          .: {}
-          f:isopod.getcruise.com/context: {}
-        f:labels:
-          .: {}
-          f:heritage: {}
-      f:spec:
-        f:conversion:
-          .: {}
-          f:strategy: {}
-        f:group: {}
-        f:names:
-          f:kind: {}
-          f:listKind: {}
-          f:plural: {}
-          f:shortNames: {}
-          f:singular: {}
-        f:preserveUnknownFields: {}
-        f:scope: {}
-        f:validation:
-          .: {}
-          f:openAPIV3Schema:
-            .: {}
-            f:properties:
-              .: {}
-              f:spec:
-                .: {}
-                f:properties:
-                  .: {}
-                  f:cronSpec:
-                    .: {}
-                    f:type: {}
-                  f:deepField:
-                    .: {}
-                    f:properties:
-                      .: {}
-                      f:attribute1:
-                        .: {}
-                        f:type: {}
-                      f:attribute2:
-                        .: {}
-                        f:type: {}
-                      f:attribute3:
-                        .: {}
-                        f:type: {}
-                    f:type: {}
-                  f:image:
-                    .: {}
-                    f:type: {}
-                  f:replicas:
-                    .: {}
-                    f:type: {}
-                f:type: {}
-            f:type: {}
-        f:version: {}
-        f:versions: {}
-      f:status:
-        f:storedVersions: {}
-  - manager: kube-apiserver
-    operation: Update
-    apiVersion: apiextensions.k8s.io/v1
-    time: "2020-05-22T17:45:33Z"
-    fieldsType: FieldsV1
-    fieldsV1:
-      f:status:
-        f:acceptedNames:
-          f:kind: {}
-          f:listKind: {}
-          f:plural: {}
-          f:shortNames: {}
-          f:singular: {}
-        f:conditions: {}