testing/minio: mark as restricted

testing/minio/APKBUILD

 # Contributor: Carlo Landmeter <clandmeter@alpinelinux.org>
 # Maintainer: Chloe Kudryavtsev <toast@toast.cafe>
+
+# RESTRICTED: Do not upgrade to any version licensed under AGPL.  No evidence
+# has been found supporting the existence of a CLA or relicensing campaign,
+# so we cannot confirm the legal validity of the license change.  Accordingly,
+# any commit upgrading the version to an AGPL-licensed version WILL be reverted.
+
 pkgname=minio
 _pkgver='RELEASE.2021-01-16T02-19-44Z'
 pkgver=${_pkgver#*.}