feat: switch from flake-parts and devenv to rensa ecosystem

tests/fixtures/flake_parts/flake.nix

@@ -0,0 +1,37 @@
+{
+  outputs = {
+    flake-parts,
+    systems,
+    ...
+  } @ inputs:
+    flake-parts.lib.mkFlake {inherit inputs;} {
+      imports = [
+        "@repo_path@/lib/flakeModule.nix"
+      ];
+      systems = import systems;
+      flake = {};
+      perSystem = _: {
+        nixible = {
+          "hello".playbook = [
+            {
+              name = "Hello World";
+              hosts = "localhost";
+              tasks = [
+                {
+                  name = "Say hello";
+                  debug.msg = "Hello from Nixible!";
+                }
+              ];
+            }
+          ];
+          "test".playbook = [];
+        };
+      };
+    };
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+    systems.url = "github:nix-systems/default-linux";
+  };
+}