tsm-client: fix lvm2 support

lvm2 support was broken when lvm2 got
converted to a multiple-output derivation:

https://github.com/NixOS/nixpkgs/pull/93024
d3a991d410

The `runtimeDependencies` attribute doesn't specifically
look for a `lib` output, so it uses the main `out` output
which no longer contains the library object files.

Since TSM loads the `libdevmapper.so` library
dynamically (likely with `dlfcn.h` functions),
the breakage couldn't be detected at build time.

The commit at hand simply uses
`getLib` to pick the correct output.

pkgs/tools/backup/tsm-client/default.nix

@@ -91,7 +91,7 @@ let
       zlib
     ];
     runtimeDependencies = [
-      lvm2
+      (lib.attrsets.getLib lvm2)
     ];
     sourceRoot = ".";