add mockito import

Author: evanliu048

plugins/amazonq/codewhisperer/jetbrains-community/tst/software/aws/toolkits/jetbrains/services/codewhisperer/CodeWhispererTestBase.kt

@@ -27,6 +27,7 @@ import org.mockito.kotlin.spy
 import org.mockito.kotlin.stub
 import org.mockito.kotlin.timeout
 import org.mockito.kotlin.verify
+import org.mockito.kotlin.whenever
 import software.amazon.awssdk.services.codewhispererruntime.CodeWhispererRuntimeClient
 import software.amazon.awssdk.services.codewhispererruntime.model.GenerateCompletionsRequest
 import software.amazon.awssdk.services.codewhispererruntime.paginators.GenerateCompletionsIterable