16053: Upgrade mockito for JDK 11 compatibility.

16053: Upgrade mockito for JDK 11 compatibility.

Fixes:

17:19:59.486 [DEBUG] [TestEventLogger] org.arvados.client.logic.keep.FileDownloaderTest STARTED
17:19:59.573 [DEBUG] [TestEventLogger]
17:19:59.573 [DEBUG] [TestEventLogger] org.arvados.client.logic.keep.FileDownloaderTest > classMethod STARTED
17:19:59.593 [DEBUG] [TestEventLogger]
17:19:59.594 [DEBUG] [TestEventLogger] org.arvados.client.logic.keep.FileDownloaderTest > classMethod FAILED
17:19:59.594 [DEBUG] [TestEventLogger]     org.mockito.exceptions.base.MockitoException:
17:19:59.594 [DEBUG] [TestEventLogger]     Mockito cannot mock this class: class org.arvados.client.api.client.CollectionsApiClient.
17:19:59.594 [DEBUG] [TestEventLogger]
17:19:59.594 [DEBUG] [TestEventLogger]     If you're not sure why you're getting this error, please report to the mailing list.
17:19:59.594 [DEBUG] [TestEventLogger]
17:19:59.594 [DEBUG] [TestEventLogger]
17:19:59.594 [DEBUG] [TestEventLogger]     Java               : 11
17:19:59.595 [DEBUG] [TestEventLogger]     JVM vendor name    : Debian
17:19:59.595 [DEBUG] [TestEventLogger]     JVM vendor version : 11.0.6+10-post-Debian-1deb10u1
17:19:59.595 [DEBUG] [TestEventLogger]     JVM name           : OpenJDK 64-Bit Server VM
17:19:59.595 [DEBUG] [TestEventLogger]     JVM version        : 11.0.6+10-post-Debian-1deb10u1
17:19:59.595 [DEBUG] [TestEventLogger]     JVM info           : mixed mode, sharing
17:19:59.595 [DEBUG] [TestEventLogger]     OS name            : Linux
17:19:59.595 [DEBUG] [TestEventLogger]     OS version         : 4.9.0-12-amd64
17:19:59.595 [DEBUG] [TestEventLogger]
17:19:59.595 [DEBUG] [TestEventLogger]
17:19:59.595 [DEBUG] [TestEventLogger]     You are seeing this disclaimer because Mockito is configured to create inlined mocks.
17:19:59.595 [DEBUG] [TestEventLogger]     You can learn about inline mocks and their limitations under item #39 of the Mockito class javadoc.
17:19:59.595 [DEBUG] [TestEventLogger]
17:19:59.595 [DEBUG] [TestEventLogger]     Underlying exception : org.mockito.exceptions.base.MockitoException: Could not modify all classes [class java.lang.Object, class org.arvados.client.api.client.BaseApiClient, class org.arvados.client.api.client.CollectionsApiClient, class org.arvados.client.api.client.BaseStandardApiClient]
17:19:59.595 [DEBUG] [TestEventLogger]         at org.mockito.internal.runners.DefaultInternalRunner$1.withBefores(DefaultInternalRunner.java:38)

Arvados-DCO-1.1-Signed-off-by: Tom Clegg <tom@tomclegg.ca>