message: build, qt: (Re-)sign package
  Starting with macOS 11 on Apple silicon, executables must be signed
  before they are allowed to run.
diff: # along with this program. If not, see <http://www.gnu.org/licenses/>.
  #
  -import sys, re, os, shutil, stat, os.path
  +import sys, re, os, platform, shutil, stat, subprocess, os.path
  from argparse import ArgumentParser
  from ds_store import DSStore
  from mac_alias import Alias
  @@ -541,6 +541,9 @@ ds.close()
  # ------------------------------------------------
  +if platform.system() == "Darwin":
  + subprocess.check_call(f"codesign --deep --force --sign - {target}", shell=True)
  +
  if config.dmg is not None:
  print("+ Preparing .dmg disk image +")
  