caddy: 0.11.1 -> 0.11.4

[dtzWill]

https://github.com/mholt/caddy/releases/tag/v0.11.4

FWIW,
versions between had regressions/bugs and shouldn't be used:

https://github.com/mholt/caddy/releases/tag/v0.11.3
https://github.com/mholt/caddy/releases/tag/v0.11.2

Motivation for this change

General Q/A note: we have a NixOS module but no NixOS test for this.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Assured whether relevant documentation is up to date
• Fits CONTRIBUTING.md.

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