treewide: fix double quoted strings in meta.description

Signed-off-by: Ben Siraphob <bensiraphob@gmail.com>

nixos/modules/services/backup/bacula.nix

@@ -190,8 +190,7 @@ let
       };
 
       devices = mkOption {
-        description = ''
-        '';
+        description = "";
       };
 
       extraAutochangerConfig = mkOption {

nixos/modules/services/backup/tarsnap.nix

@@ -354,7 +354,7 @@ in
 
         script = let
           tarsnap = ''tarsnap --configfile "/etc/tarsnap/${name}.conf"'';
-          lastArchive = ''$(${tarsnap} --list-archives | sort | tail -1)'';
+          lastArchive = "$(${tarsnap} --list-archives | sort | tail -1)";
           run = ''${tarsnap} -x -f "${lastArchive}" ${optionalString cfg.verbose "-v"}'';
 
         in if (cfg.cachedir != null) then ''