scripts/get-version: Select stable release for test when newer

The release list is already ordered newest first, so the test channel
only needs to consider releases that are either prereleases or the
latest stable release.
This keeps test from resolving to an older prerelease after a newer
stable release is published.

Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>

Author: vvoland

scripts/get-version.sh

@@ -21,7 +21,7 @@ last_release_tag() {
 
 case "$channel" in
     stable) last_release_tag 'isLatest' ;;
-    test) last_release_tag 'isPrerelease' ;;
+    test) last_release_tag 'isPrerelease or .isLatest' ;;
     *)
         echo "Error: Invalid channel '$channel'. Use 'stable' or 'test'." >&2
         exit 1