use callPackage for merge-after-ci, nix-unit & tea-create-pr

pkgs/merge-after-ci/default.nix

@@ -1,27 +1,23 @@
-{
-  perSystem =
-    { pkgs
-    , self'
-    , ...
-    }:
-    let
-      name = builtins.baseNameOf ./.;
-      script = pkgs.writeShellApplication {
-        inherit name;
-        runtimeInputs = [
-          pkgs.bash
-          pkgs.coreutils
-          pkgs.git
-          pkgs.tea
-          pkgs.openssh
-          self'.packages.tea-create-pr
-        ];
-        text = ''
-          bash ${./script.sh} "$@"
-        '';
-      };
-    in
-    {
-      packages.${name} = script;
-    };
+{ writeShellApplication
+, coreutils
+, bash
+, git
+, tea
+, openssh
+, tea-create-pr
+, ...
+}:
+writeShellApplication {
+  name = "merge-after-ci";
+  runtimeInputs = [
+    bash
+    coreutils
+    git
+    tea
+    openssh
+    tea-create-pr
+  ];
+  text = ''
+    bash ${./script.sh} "$@"
+  '';
 }