treefmt/tests: Fix whitespace

Fix whitespace in the following `treefmt.tests`:
- buildConfigExample
- buildConfigModules

The test failure was introduced in `f80b06e6d872f3b7f24212ef5d1773fc9d478b3e`,
when the `remarshal` package, that is used for `toml` generation updated
it's `tomlkit` dependency from `0.13.2 -> 0.13.3` in the following commit: [387].

[387]: https://github.com/python-poetry/tomlkit/issues/387

pkgs/by-name/tr/treefmt/tests.nix

@@ -45,6 +45,7 @@ in
     expected = ''
       on-unmatched = "info"
       tree-root-file = ".git/index"
+
       [formatter.nixfmt]
       command = "nixfmt"
       includes = ["*.nix"]
@@ -60,6 +61,7 @@ in
     expected = ''
       on-unmatched = "info"
       tree-root-file = "overridden"
+
       [formatter.nixfmt]
       command = "nixfmt"
       includes = ["*.nix"]