ibmvpc: Add version parameter to VpcV1

As of ibm-vpc 0.28.0, a version parameter is required. [1]
The old default value for the version was "2025-03-04", but the
documentation states that the min value is now "2025-04-08". Setting
this min value as the version to try and be compatible to the previous
value.

This fixes failing tests for the ibmvpc driver.

[1] https://github.com/IBM/vpc-python-sdk/pull/88

Change-Id: I351af87d8e47e71c2d5dd2ef0820e430e1f5b9ee

nodepool/driver/ibmvpc/adapter.py

@@ -361,7 +361,8 @@ class IBMVPCAdapter(statemachine.Adapter):
         if self.provider.credentials_file:
             os.environ['IBM_CREDENTIALS_FILE'] = self.provider.credentials_file
         authenticator = get_authenticator_from_environment('vpc')
-        self.cloud_vpc = VpcV1(authenticator=authenticator)
+        self.cloud_vpc = VpcV1(
+            authenticator=authenticator, version="2025-04-08")
         # Set the service URL to our region
         service_url = f"https://{self.provider.region}.iaas.cloud.ibm.com/v1"
         self.cloud_vpc.set_service_url(service_url)