chore: remove nix flake

.gitignore

@@ -1,3 +1,2 @@
 /target/
 /Cargo.lock
-/flake.lock

flake.nix

@@ -1,27 +0,0 @@
-{
-    description = "crdt-enc";
-
-    inputs = {
-        nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable-small";
-        flake-utils.url = "github:numtide/flake-utils";
-    };
-
-    outputs = { self, flake-utils, nixpkgs }:
-        flake-utils.lib.eachDefaultSystem (system:
-            let
-                pkgs = import nixpkgs { inherit system; };
-            in {
-                devShell = pkgs.stdenv.mkDerivation {
-                    name = "crdt-enc";
-                    buildInputs = [
-                        pkgs.gpgme
-
-                        pkgs.cargo
-                        pkgs.rustc
-                        pkgs.rustfmt
-                        pkgs.rust-analyzer
-                    ];
-                };
-            }
-        );
-}