libapparmor: support python 3.8

pkgs/os-specific/linux/apparmor/default.nix

···
     # (alpine patches {1,4,5,6,8} are needed for apparmor 2.11, but not 2.12)
     ] ++ [
       ./cross.patch
+      # Support Python 3.8
+      (fetchpatch {
+        url = https://gitlab.com/apparmor/apparmor/commit/ccbf1e0bf1bf5c3bbab47029fbbc5415ef73bac1.patch;
+        sha256 = "0kfzc0wyjybj38n10yvwakaaqvglalzigd3kk7gcrbp1xdn70pq2";
+      })
     ];
 
   # Set to `true` after the next FIXME gets fixed or this gets some