style: from __future__ import annotations in every .py file with code

coverage/__init__.py

@@ -9,6 +9,8 @@
 
 """
 
+from __future__ import annotations
+
 # mypy's convention is that "import as" names are public from the module.
 # We import names as themselves to indicate that. Pylint sees it as pointless,
 # so disable its warning.

coverage/__main__.py

@@ -3,6 +3,8 @@
 
 """Coverage.py's main entry point."""
 
+from __future__ import annotations
+
 import sys
 from coverage.cmdline import main
 sys.exit(main())

coverage/exceptions.py

@@ -3,6 +3,7 @@
 
 """Exceptions coverage.py can raise."""
 
+from __future__ import annotations
 
 class _BaseCoverageException(Exception):
     """The base-base of all Coverage exceptions."""

coverage/multiproc.py

@@ -3,6 +3,8 @@
 
 """Monkey-patching to add multiprocessing support for coverage.py"""
 
+from __future__ import annotations
+
 import multiprocessing
 import multiprocessing.process
 import os

tests/test_oddball.py

@@ -3,6 +3,8 @@
 
 """Oddball cases for testing coverage.py"""
 
+from __future__ import annotations
+
 import os.path
 import re
 import sys

tests/test_phystokens.py

@@ -3,6 +3,8 @@
 
 """Tests for coverage.py's improved tokenizer."""
 
+from __future__ import annotations
+
 import os.path
 import re
 import textwrap