To the flake as well

flake.nix

@@ -190,6 +190,11 @@
           description = "Rust development environment";
         };
 
+        rustpython = {
+          path = ./rustpython;
+          description = "Rustpython development environment";
+        };
+
         rust-toolchain = {
           path = ./rust-toolchain;
           description = "Rust development environment with Rust version defined by a rust-toolchain.toml file";