python: simplify code in Package.collect()

The path of Package is already the `__init__.py` file, and we're already
assured it's a file.

src/_pytest/python.py

@@ -745,11 +745,11 @@ class Package(Module):
 
     def collect(self) -> Iterable[Union[nodes.Item, nodes.Collector]]:
         this_path = self.path.parent
-        init_module = this_path / "__init__.py"
-        if init_module.is_file() and path_matches_patterns(
-            init_module, self.config.getini("python_files")
-        ):
-            yield Module.from_parent(self, path=init_module)
+
+        # Always collect the __init__ first.
+        if path_matches_patterns(self.path, self.config.getini("python_files")):
+            yield Module.from_parent(self, path=self.path)
+
         pkg_prefixes: Set[Path] = set()
         for direntry in visit(str(this_path), recurse=self._recurse):
             path = Path(direntry.path)