nix: simplify maintainers handling (repology/repology-rs#343)

We don't need unicalization here

Author: AMDmi3

repology/parsers/parsers/nix.py

@@ -219,14 +219,12 @@ def iter_parse(self, path: str, factory: PackageFactory) -> Iterable[PackageMake
                     pkg.set_summary(meta['description'].replace('\n', ' '))
 
                 if 'maintainers' in meta:
-                    # unlike dict, python set does not preserve order which is required here
-                    # so simulate set with dict until we drop python implementation
-                    maintainers = {m: None for m in extract_nix_maintainers(meta['maintainers'])}
+                    maintainers = list(extract_nix_maintainers(meta['maintainers']))
 
                     if len(maintainers) > 20:
-                        raise RuntimeError(f'too many maintainers ({len(maintainers)}: {", ".join(sorted(maintainers))}) for a single package')
+                        raise RuntimeError(f'too many maintainers ({len(maintainers)}: {", ".join(maintainers)}) for a single package')
 
-                    pkg.add_maintainers(maintainers.keys())
+                    pkg.add_maintainers(maintainers)
                     max_maintainers = max(max_maintainers, len(maintainers))
 
                 if 'license' in meta: