Add a lot of type annotations

src/ocrmypdf/pluginspec.py

@@ -19,13 +19,17 @@ from abc import ABC, abstractmethod, abstractstaticmethod
 from argparse import ArgumentParser, Namespace
 from collections import namedtuple
 from pathlib import Path
-from typing import AbstractSet, List, Optional
+from typing import TYPE_CHECKING, AbstractSet, List, Optional
 
 import pluggy
 from PIL import Image
 
 from ocrmypdf.helpers import Resolution
 
+if TYPE_CHECKING:
+    from ocrmypdf._jobcontext import PageContext
+    from ocrmypdf.pdfinfo import PdfInfo
+
 hookspec = pluggy.HookspecMarker('ocrmypdf')
 
 # pylint: disable=unused-argument