librepo: 1.7.20 -> 1.8.1

[c0bw3b]

Motivation for this change

Version bump

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option build-use-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/)
• Fits CONTRIBUTING.md.

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[c0bw3b]

@copumpkin for review

The patchPhase is not necessary anymore thanks to this commit.

[copumpkin]

Cool, thanks!