Add two shell.nix to enable easier development on nixos.

shell.nix

@@ -0,0 +1,23 @@
+# This is meant for use with the nix package manager. If you don't know what it is or don't use it, please ignore this file.
+#
+# This shell.nix contains all dependencies require to create a venv and pip install -r requirements.txt.
+#
+# Please check shell-static.nix for
+{ pkgs ? import <nixpkgs> {} }:
+pkgs.mkShell {
+  buildInputs = with pkgs; [
+    python39
+    python39Packages.pip
+    python39Packages.setuptools
+    gettext
+
+  ];
+  shellHook = ''
+    # Tells pip to put packages into $PIP_PREFIX instead of the usual locations.
+    # See https://pip.pypa.io/en/stable/user_guide/#environment-variables.
+    export PIP_PREFIX=$(pwd)/_build/pip_packages
+    export PYTHONPATH="$PIP_PREFIX/${pkgs.python39.sitePackages}:$PYTHONPATH"
+    export PATH="$PIP_PREFIX/bin:$PATH"
+    unset SOURCE_DATE_EPOCH
+  '';
+}