mass replace "flip map -> forEach"

See `forEach`-introduction commit.
```
rg 'flip map ' --files-with-matches | xargs sed -i 's/flip map /forEach /g'
```

nixos/modules/services/networking/hylafax/systemd.nix

@@ -7,7 +7,7 @@ let
   inherit (lib) concatStringsSep optionalString;
 
   cfg = config.services.hylafax;
-  mapModems = lib.flip map (lib.attrValues cfg.modems);
+  mapModems = lib.forEach (lib.attrValues cfg.modems);
 
   mkConfigFile = name: conf:
     # creates hylafax config file,