add type stub packages

requirements/dev.txt

@@ -141,6 +141,8 @@ tomli==1.2.1
     # via pep517
 tox==3.24.1
     # via -r requirements/dev.in
+types-contextvars==0.1.4
+    # via -r requirements/typing.in
 types-dataclasses==0.1.7
     # via -r requirements/typing.in
 types-setuptools==57.0.2

requirements/typing.in

@@ -1,4 +1,5 @@
 mypy
+types-contextvars
 types-dataclasses
 types-setuptools
 cryptography

requirements/typing.txt

@@ -16,6 +16,8 @@ pycparser==2.20
     # via cffi
 toml==0.10.2
     # via mypy
+types-contextvars==0.1.4
+    # via -r requirements/typing.in
 types-dataclasses==0.1.7
     # via -r requirements/typing.in
 types-setuptools==57.0.2