GHSA-7RP8-R62P-Q6WC `melange update-cache` has unbounded HTTP download that can exhaust disk in CI

melange update-cache downloads URIs from build configs via io.Copy without any size limit or HTTP client timeout pkg/renovate/cache/cache.go. An attacker-controlled URI in a melange config can cause unbounded disk writes, exhausting disk on the build runner. Affected versions = 0.40.5. Fix: Merge...