Add __all__ part 2 (#13719)

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Co-authored-by: Avasam <samuel.06@hotmail.com>

stubs/libsass/sassutils/builder.pyi

@@ -32,3 +32,5 @@ class Manifest:
     def unresolve_filename(self, package_dir: str, filename: str) -> str: ...
     def build(self, package_dir: str, output_style: _OutputStyle = "nested") -> frozenset[str]: ...
     def build_one(self, package_dir: str, filename: str, source_map: bool = False) -> str: ...
+
+__all__ = ("SUFFIXES", "SUFFIX_PATTERN", "Manifest", "build_directory")

stubs/libsass/sassutils/distutils.pyi

@@ -14,3 +14,5 @@ class build_sass(Command):
     def finalize_options(self) -> None: ...
     def run(self) -> None: ...
     def get_package_dir(self, package: str) -> str: ...
+
+__all__ = ("build_sass", "validate_manifests")

stubs/libsass/sassutils/wsgi.pyi

@@ -20,3 +20,5 @@ class SassMiddleware:
     def __call__(self, environ: WSGIEnvironment, start_response: StartResponse) -> Iterable[bytes]: ...
     @staticmethod
     def quote_css_string(s: str) -> str: ...
+
+__all__ = ("SassMiddleware",)