nixos/pay-respects: fix "(eval):1: parse error near `alias'"

The README of pay-respects recommends the following for Bash and Zsh:
```sh
eval "$(pay-respects bash --alias)"
eval "$(pay-respects zsh --alias)"
```
The code in the NixOS module is missing the quotes.
This causes "(eval):1: parse error near `alias'" for me (using Zsh) and the alias `f` does not work.

Luflosi 732a1dca e6625a21

Changed files
+1 -1
nixos
modules
programs
+1 -1
nixos/modules/programs/pay-respects.nix
···
shell:
if (shell != "fish") then
''
-
eval $(${getExe finalPackage} ${shell} --alias ${cfg.alias})
+
eval "$(${getExe finalPackage} ${shell} --alias ${cfg.alias})"
''
else
''