feat(gkehub): update the API

#### gkehub:v1

The following keys were added:
- schemas.Authority.properties.oidcJwks.description
- schemas.Authority.properties.oidcJwks.format
- schemas.Authority.properties.oidcJwks.type

discovery/gkehub-v1.json

@@ -631,7 +631,7 @@
       }
     }
   },
-  "revision": "20210507",
+  "revision": "20210512",
   "rootUrl": "https://gkehub.googleapis.com/",
   "schemas": {
     "AuditConfig": {
@@ -695,6 +695,11 @@
           "description": "Optional. A JSON Web Token (JWT) issuer URI. `issuer` must start with `https://` and be a valid URL with length <2000 characters. If set, then Google will allow valid OIDC tokens from this issuer to authenticate within the workload_identity_pool. OIDC discovery will be performed on this URI to validate tokens from the issuer. Clearing `issuer` disables Workload Identity. `issuer` cannot be directly modified; it must be cleared (and Workload Identity disabled) before using a new issuer (and re-enabling Workload Identity).",
           "type": "string"
         },
+        "oidcJwks": {
+          "description": "Optional. OIDC verification keys for this Membership in JWKS format (RFC 7517). When this field is set, OIDC discovery will NOT be performed on `issuer`, and instead OIDC tokens will be validated using this field.",
+          "format": "byte",
+          "type": "string"
+        },
         "workloadIdentityPool": {
           "description": "Output only. The name of the workload identity pool in which `issuer` will be recognized. There is a single Workload Identity Pool per Hub that is shared between all Memberships that belong to that Hub. For a Hub hosted in {PROJECT_ID}, the workload pool format is `{PROJECT_ID}.hub.id.goog`, although this is subject to change in newer versions of this API.",
           "readOnly": true,

src/apis/gkehub/v1.ts

@@ -163,6 +163,10 @@ export namespace gkehub_v1 {
      * Optional. A JSON Web Token (JWT) issuer URI. `issuer` must start with `https://` and be a valid URL with length <2000 characters. If set, then Google will allow valid OIDC tokens from this issuer to authenticate within the workload_identity_pool. OIDC discovery will be performed on this URI to validate tokens from the issuer. Clearing `issuer` disables Workload Identity. `issuer` cannot be directly modified; it must be cleared (and Workload Identity disabled) before using a new issuer (and re-enabling Workload Identity).
      */
     issuer?: string | null;
+    /**
+     * Optional. OIDC verification keys for this Membership in JWKS format (RFC 7517). When this field is set, OIDC discovery will NOT be performed on `issuer`, and instead OIDC tokens will be validated using this field.
+     */
+    oidcJwks?: string | null;
     /**
      * Output only. The name of the workload identity pool in which `issuer` will be recognized. There is a single Workload Identity Pool per Hub that is shared between all Memberships that belong to that Hub. For a Hub hosted in {PROJECT_ID\}, the workload pool format is `{PROJECT_ID\}.hub.id.goog`, although this is subject to change in newer versions of this API.
      */