🐛 fix signed-releases lookback limit precedence #4060

if the 6th release had no assets, the lookback limit exit condition was being skipped. This led to scenarios where too many releases were being considered by the Signed-Releases check. ossf#4059 Signed-off-by: Spencer Schrock <[email protected]>

any release after the lookback should be skipped Signed-off-by: Spencer Schrock <[email protected]>