Update BuildOptions description

Co-Authored-By: Joe Rickerby <joerick@mac.com>

cibuildwheel/util.py

@@ -124,21 +124,8 @@ BuildOptions = NamedTuple("BuildOptions", [
 ])
 
 """
-when drop support of python 3.5 execution.
-class BuildOptions(NamedTuple):
-    project_dir: str
-    output_dir: str
-    test_command: Optional[str]
-    test_requires: List[str]
-    test_extras: str
-    before_build: Optional[str]
-    build_verbosity: int
-    build_selector: BuildSelector
-    repair_command: str
-    environment: ParsedEnvironment
-    before_test: str
-    dependency_constraints: Optional[DependencyConstraints]
-    manylinux_images: Optional[Dict[str, str]]
+Replace this definition with a class-style NamedTuple in the
+PEP526 style when Python 3.5 host support is dropped
 """
 
 resources_dir = os.path.abspath(os.path.join(os.path.dirname(__file__), 'resources'))