feat(tpu): update the API

#### tpu:v2alpha1

The following keys were added:
- schemas.SchedulingConfig.properties.reservationName.description
- schemas.SchedulingConfig.properties.reservationName.type

Author: yoshi-automation

discovery/tpu-v2alpha1.json

@@ -1027,7 +1027,7 @@
       }
     }
   },
-  "revision": "20250423",
+  "revision": "20250616",
   "rootUrl": "https://tpu.googleapis.com/",
   "schemas": {
     "AcceleratorConfig": {
@@ -2235,6 +2235,10 @@
           ],
           "type": "string"
         },
+        "reservationName": {
+          "description": "Optional. Name of the reservation in which the node should be provisioned.",
+          "type": "string"
+        },
         "reserved": {
           "description": "Whether the node is created under a reservation.",
           "type": "boolean"