Fixed AttributeError in the packaging script when using python>=3.8.

platform.dist() is deprecated since python version 3.5 and was removed in version 3.8.
Added exception to use the distro package in that case, as suggested by the python documentation:
https://docs.python.org/3.7/library/platform.html?highlight=platform#module-platform

package.py

@@ -212,7 +212,11 @@ def main():
         package_windows()
     else:
         if not args.arch_pkg:
-            distname, _, _ = platform.dist()
+            try:
+              distname, _, _ = platform.dist()
+            except AttributeError:
+              import distro
+              distname, _, _ = distro.linux_distribution(full_distribution_name=False)
         else:
             distname = "arch"
         if distname == "arch":