Update min apk version/add more apk version checks

* Minimum version: 2.7.2 (which fixes two CVEs)
* Check the minimum apk version before doing something with apk and
  before entering the chroot manually (previously, it has just checked
  the apk-tools-static version, which gets used to set up the chroot)
* Reword the message for an outdated APK version. Most likely it is
  just the outdated http cache, instead of a man-in-the-middle attack.

See also:
b849b481a0

pmbootstrap.py

@@ -66,6 +66,7 @@ def main():
         elif args.action == "checksum":
             pmb.build.checksum(args, args.package)
         elif args.action == "chroot":
+            pmb.chroot.apk.check_min_version(args, args.suffix)
             pmb.chroot.root(args, args.command, args.suffix, log=False)
         elif args.action == "index":
             pmb.build.index_repo(args)