Update gotestsum to add timestamps to junit output

The current release of gotestsum is missing timestamps in the junit
data, which makes it difficult to import in an external system later.

gotestyourself/gotestsum@012a85e
includes the necessary changes to add the timestamp for the test run to
the junit output.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
(cherry picked from commit bfbebf0)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

script/setup/install-gotestsum

@@ -14,4 +14,4 @@
 #   See the License for the specific language governing permissions and
 #   limitations under the License.
 
-GO111MODULE=on go install gotest.tools/gotestsum@v1.6.2
+GO111MODULE=on go install gotest.tools/gotestsum@012a85e34a7ce5554057d512e55dcb54b6f2505e