pkgs: add woodpecker

This is just the same version as upstream, but following the `next`
version.

pkgs/woodpecker/cli.nix

@@ -0,0 +1,16 @@
+{ lib, buildGoModule, callPackage, fetchFromGitHub }:
+let
+  common = callPackage ./common.nix { };
+in
+buildGoModule {
+  pname = "woodpecker-cli";
+  inherit (common) version src ldflags postInstall vendorHash;
+
+  subPackages = "cmd/cli";
+
+  CGO_ENABLED = 0;
+
+  meta = common.meta // {
+    description = "Command line client for the Woodpecker Continuous Integration server";
+  };
+}