fix(vmmigration): update the API

#### vmmigration:v1alpha1

The following keys were changed:
- schemas.NetworkInterface.properties.network.description

#### vmmigration:v1

The following keys were changed:
- schemas.NetworkInterface.properties.network.description

Author: yoshi-automation

discovery/vmmigration-v1.json

@@ -2254,7 +2254,7 @@
       }
     }
   },
-  "revision": "20250717",
+  "revision": "20250724",
   "rootUrl": "https://vmmigration.googleapis.com/",
   "schemas": {
     "AccessKeyCredentials": {
@@ -5151,7 +5151,7 @@
           "type": "string"
         },
         "network": {
-          "description": "The network to connect the NIC to.",
+          "description": "Optional. The network to connect the NIC to.",
           "type": "string"
         },
         "networkTier": {

discovery/vmmigration-v1alpha1.json

@@ -2254,7 +2254,7 @@
       }
     }
   },
-  "revision": "20250717",
+  "revision": "20250724",
   "rootUrl": "https://vmmigration.googleapis.com/",
   "schemas": {
     "AccessKeyCredentials": {
@@ -5196,7 +5196,7 @@
           "type": "string"
         },
         "network": {
-          "description": "The network to connect the NIC to.",
+          "description": "Optional. The network to connect the NIC to.",
           "type": "string"
         },
         "networkTier": {

src/apis/vmmigration/v1.ts

@@ -1985,7 +1985,7 @@ export namespace vmmigration_v1 {
      */
     internalIp?: string | null;
     /**
-     * The network to connect the NIC to.
+     * Optional. The network to connect the NIC to.
      */
     network?: string | null;
     /**

src/apis/vmmigration/v1alpha1.ts

@@ -2014,7 +2014,7 @@ export namespace vmmigration_v1alpha1 {
      */
     internalIp?: string | null;
     /**
-     * The network to connect the NIC to.
+     * Optional. The network to connect the NIC to.
      */
     network?: string | null;
     /**