repart-image: removing unshare (and util-linux dep) form systemd-repart invocation

..

nixos/modules/image/repart-image.nix

@@ -10,7 +10,6 @@
 , mypy
 , systemd
 , fakeroot
-, util-linux
 
   # filesystem tools
 , dosfstools
@@ -105,7 +104,6 @@ in
   nativeBuildInputs = [
     systemd
     fakeroot
-    util-linux
   ] ++ lib.optionals (compression.enable) [
     compressionPkg
   ] ++ fileSystemTools;
@@ -148,7 +146,7 @@ in
     runHook preBuild
 
     echo "Building image with systemd-repart..."
-    unshare --map-root-user fakeroot systemd-repart \
+    fakeroot systemd-repart \
       ''${systemdRepartFlags[@]} \
       ${imageFileBasename}.raw \
       | tee repart-output.json