If the upstream is GIT and version is not a hash, updater will try to
list upstream tags to find a newer version. And suggest to merge from
that tag.

Change-Id: I34651815c761c78fd0485df0a84adc086a810e9e
Test: Change googletest/METADATA to follow upstream releases. And run updater.

Bug: 109748616
Test: https://android-review.googlesource.com/c/platform/external/kotlinc/+/699886
Change-Id: I1c28aa256bca6ee5be1ea15f295c5e0fa63526d1