Update robolectric dependency to v3.6.2.

This is required for support of v53 .class files.

Test: The following tests pass both before and after this CL:
      make RunFrameworksServicesRoboTests RunBluetoothRoboTests \
           RunCarMessengerRoboTests RunKeyChainRoboTests \
      RunManagedProvisioningRoboTests
Test: The above tests also pass when EXPERIMENTAL_USE_OPENJDK9=true
      (they didn't pass with v3.6.1).
Test: The following tests fail both before and after this CL (error
      trying to mock a final class):
      make RunStorageManagerRoboTests RunEmergencyInfoRoboTests

Bug: 116872534
Change-Id: I0777e190e831145b16776e2e31daf613969ef62e