Add dry-build action

Flake lock file updates:

• Updated input 'disko':
    'github:nix-community/disko/d57058eb09dd5ec00c746df34fe0a603ea744370' (2024-05-02)
  → 'github:nix-community/disko/e1b3ae2b4ebc3c7b83154b9361e3d154e64e362d' (2024-05-06)
• Updated input 'nixos-hardware':
    'github:NixOS/nixos-hardware/753176b57b3fcddb140c1c012868e62c025120bd' (2024-05-05)
  → 'github:NixOS/nixos-hardware/e148ccbecbd2fe4dc4768fba67f6db828466ad06' (2024-05-06)
• Updated input 'nixpkgs-unstable':
    'github:NixOS/nixpkgs/e9be42459999a253a9f92559b1f5b72e1b44c13d' (2024-05-03)
  → 'github:NixOS/nixpkgs/25865a40d14b3f9cf19f19b924e2ab4069b09588' (2024-05-05)
• Updated input 'secrets':
    'git+ssh://git@git.vimium.com/jordan/nix-secrets.git?ref=refs/heads/master&rev=f350d35d7651c415fa4c0d6a7cff378ba5650f93' (2024-04-01)
  → 'git+ssh://git@git.vimium.com/jordan/nix-secrets.git?ref=refs/heads/master&rev=b4a1c8968a1cb3688c12caddecd99432494df95b' (2024-05-06)

modules/services/gitea-runner/default.nix

@@ -208,7 +208,7 @@ in
           container = {
             options = "-e NIX_BUILD_SHELL=/bin/bash -e PAGER=cat -e PATH=/bin -e SSL_CERT_FILE=/etc/ssl/certs/ca-bundle.crt --device /dev/kvm -v /nix:/nix -v ${storeDeps}/bin:/bin -v ${storeDeps}/etc/ssl:/etc/ssl --user nix-ci-user";
             network = "host";
-            validVolumes = [
+            valid_volumes = [
               "/nix"
               "${storeDeps}/bin"
               "${storeDeps}/etc/ssl"