message: Fix deserialization issue in AdmissionResponse
  Fix deserialization issue in AdmissionResponse - fixes
  This prevented unit testing the responses.
diff: @@ -249,7 +249,7 @@ pub struct AdmissionResponse {
  /// imagepolicy.example.com/error=image-blacklisted). AuditAnnotations will
  /// be provided by the admission webhook to add additional context to the
  /// audit log for this request.
  - #[serde(skip_serializing_if = "HashMap::is_empty")]
  + #[serde(default, skip_serializing_if = "HashMap::is_empty")]
  pub audit_annotations: HashMap<String, String>,
  /// A list of warning messages to return to the requesting API client.
  /// Warning messages describe a problem the client making the API request
  