Remove tensorflow Xcode version lock (#1057)
Remove tensorflow Xcode version lock (#1057)

Tensorflow was using Xcode 10.3 which is no longer supported for App
Store uploads. This unpins the version since it should be compatible
with any Xcode version.
bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration,bazelbuild/continuous-integration