ci/eval.compare: use lib from pinned nixpkgs

compare/maintainers.nix needs to access the current checkout to check
attrpaths, but makes the mistake of using lib from that checkout as
well. All other code in ci/ uses the pinned nixpkgs instance, so
maintainers.nix should do so as well.

ci/eval/compare/default.nix

@@ -1,10 +1,10 @@
 {
+  callPackage,
   lib,
   jq,
   runCommand,
   writeText,
   python3,
-  ...
 }:
 {
   beforeResultDir,
@@ -127,7 +127,7 @@ let
       }
     );
 
-  maintainers = import ./maintainers.nix {
+  maintainers = callPackage ./maintainers.nix { } {
     changedattrs = lib.attrNames (lib.groupBy (a: a.name) rebuildsPackagePlatformAttrs);
     changedpathsjson = touchedFilesJson;
     inherit byName;

ci/eval/compare/maintainers.nix

@@ -1,3 +1,6 @@
+{
+  lib,
+}:
 # Almost directly vendored from https://github.com/NixOS/ofborg/blob/5a4e743f192fb151915fcbe8789922fa401ecf48/ofborg/src/maintainers.nix
 {
   changedattrs,
@@ -10,7 +13,6 @@ let
     config = { };
     overlays = [ ];
   };
-  inherit (pkgs) lib;
 
   changedpaths = builtins.fromJSON (builtins.readFile changedpathsjson);
 

ci/eval/default.nix

@@ -1,4 +1,5 @@
 {
+  callPackage,
   lib,
   runCommand,
   writeShellScript,
@@ -227,16 +228,7 @@ let
         done
       '';
 
-  compare = import ./compare {
+  compare = callPackage ./compare { };
-    inherit
-      lib
-      jq
-      runCommand
-      writeText
-      supportedSystems
-      python3
-      ;
-  };
 
   full =
     {