install-grub: add missing rmtree (#383269)

Author: Mic92

nixos/modules/system/boot/loader/grub/install-grub.pl

@@ -3,7 +3,7 @@
 use Class::Struct;
 use XML::LibXML;
 use File::Basename;
-use File::Path qw(make_path);
+use File::Path qw(make_path rmtree);
 use File::stat;
 use File::Copy;
 use File::Copy::Recursive qw(rcopy pathrm);