chore: yoink everything not needed for nix package

flake.nix

@@ -0,0 +1,47 @@
+{
+  inputs.nixpkgs.url = "nixpkgs/nixos-23.05";
+
+  outputs = { self, nixpkgs, systems }:
+  let
+    version = "2023.1125";
+    forEachSystem = nixpkgs.lib.genAttrs (import systems);
+    nixpkgsFor = forEachSystem (system: import nixpkgs { inherit system; });
+  in {
+    packages = forEachSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in {
+        bumpver = pkgs.python3.pkgs.buildPythonApplication rec {
+          pname = "bumpver";
+          inherit version;
+
+          src = ./.;
+
+          propagatedBuildInputs = with pkgs.python3.pkgs; [
+            pathlib2
+            click
+            toml
+            lexid
+            colorama
+            setuptools
+            rich
+            looseversion
+          ];
+
+          nativeCheckInputs = [
+            pkgs.python3.pkgs.pytestCheckHook
+            pkgs.git
+            pkgs.mercurial
+          ];
+
+          disabledTests = [
+            # fails due to more aggressive setuptools version specifier validation
+            "test_parse_default_pattern"
+          ];
+        };
+      }
+    );
+
+    defaultPackage = forEachSystem (system: self.packages.${system}.bumpver);
+  };
+}