overlays: use nixpkgs-unstable for few overlays I had

.github/workflows/cachix.yml

@@ -1,21 +0,0 @@
-name: "Build everything and push to cachix"
-on:
-  workflow_dispatch:
-  schedule:
-    - cron: '0 */4 * * *'
-  push:
-    branches:
-      - main
-jobs:
-  build:
-    runs-on: ubuntu-latest
-    steps:
-    - uses: actions/checkout@v2
-    - uses: cachix/install-nix-action@v12
-      with:
-        nix_path: nixpkgs=channel:nixos-20.09-small
-    - uses: cachix/cachix-action@v8
-      with:
-        name: alarsyo
-        authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
-    - run: nix-build ./overlays/build-me.nix

flake.nix

@@ -13,12 +13,20 @@
           ./poseidon.nix
 
           {
-            nixpkgs.overlays = [
+            nixpkgs.overlays =
+              let
+                pkgsUnstable = nixpkgs-unstable.legacyPackages.${system};
+              in
+                [
                   # packages accessible through pkgs.unstable.package
                   (final: prev: {
-                unstable = nixpkgs-unstable.legacyPackages.${system};
+                    unstable = pkgsUnstable;
                   })
-            ] ++ (import ./overlays);
+                  (final: prev: {
+                    bitwarden_rs = pkgsUnstable.bitwarden_rs;
+                    bitwarden_rs-vault = pkgsUnstable.bitwarden_rs-vault;
+                  })
+                ];
           }
         ];
     };

overlays/bitwarden_rs-vault.nix

@@ -1,11 +0,0 @@
-final: prev:
-{
-  bitwarden_rs-vault = prev.bitwarden_rs-vault.overrideAttrs (drv: rec {
-    version = "2.17.1";
-
-    src = prev.fetchurl {
-      url = "https://github.com/dani-garcia/bw_web_builds/releases/download/v${version}/bw_web_v${version}.tar.gz";
-      sha256 = "1kd21higniszk1na5ag7q4g0l7h6ddl91gpbjbwym28hsbjvxla7";
-    };
-  });
-}

overlays/bitwarden_rs.nix

@@ -1,23 +0,0 @@
-# necessary for now because I need 1.18.0, having migrated from a previous
-# deployment that used an updated Docker image
-final: prev:
-{
-  bitwarden_rs = prev.bitwarden_rs.overrideAttrs (drv: rec {
-    version = "1.18.0";
-    pname = "bitwarden_rs";
-    name = "${pname}-${version}";
-
-    src = prev.fetchFromGitHub {
-      owner = "dani-garcia";
-      repo = pname;
-      rev = version;
-      sha256 = "sha256-iK0Yf5Hu76b4FXPTQsKIsyH69CQuLA9E/SoTaxC1U90=";
-    };
-
-    cargoDeps = drv.cargoDeps.overrideAttrs (prev.lib.const {
-      inherit src;
-      name = "${name}-vendor.tar.gz";
-      outputHash = "sha256-LKLjZ4tti/MtloVQJ1C593FAcp0DDskIl5famT8wGuI=";
-    });
-  });
-}

overlays/build-me.nix

@@ -1,8 +0,0 @@
-# File used in GitHub workflow to build my overlays
-let
-  pkgs = import <nixpkgs> { overlays = import ./.; };
-in
-with pkgs; [
-  bitwarden_rs-postgresql
-  bitwarden_rs-vault
-]

overlays/default.nix

@@ -1,8 +0,0 @@
-let
-  bitwarden_rs = import ./bitwarden_rs.nix;
-  bitwarden_rs-vault = import ./bitwarden_rs-vault.nix;
-in
-[
-  bitwarden_rs
-  bitwarden_rs-vault
-]