Add Python 3.10 support

Author: pradyunsg

.github/workflows/ci.yml

@@ -96,6 +96,7 @@ jobs:
           - 3.7
           - 3.8
           - 3.9
+          - 3.10
 
     steps:
       - uses: actions/checkout@v2
@@ -137,6 +138,7 @@ jobs:
           # - 3.7
           # - 3.8
           - 3.9
+          - 3.10
         group: [1, 2]
 
     steps:

docs/html/installation.md

@@ -67,7 +67,7 @@ distro community, cloud provider support channels, etc).
 The current version of pip works on:
 
 - Windows, Linux and MacOS.
-- CPython 3.6, 3.7, 3.8, 3.9 and latest PyPy3.
+- CPython 3.6, 3.7, 3.8, 3.9, 3.10 and latest PyPy3.
 
 pip is tested to work on the latest patch version of the Python interpreter,
 for each of the minor versions listed above. Previous patch versions are

noxfile.py

@@ -70,7 +70,7 @@ def should_update_common_wheels() -> bool:
 #   completely to nox for all our automation. Contributors should prefer using
 #   `tox -e ...` until this note is removed.
 # -----------------------------------------------------------------------------
-@nox.session(python=["3.6", "3.7", "3.8", "3.9", "pypy3"])
+@nox.session(python=["3.6", "3.7", "3.8", "3.9", "3.10", "pypy3"])
 def test(session: nox.Session) -> None:
     # Get the common wheels.
     if should_update_common_wheels():

setup.py

@@ -41,6 +41,7 @@ def get_version(rel_path: str) -> str:
         "Programming Language :: Python :: 3.7",
         "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
+        "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: Implementation :: CPython",
         "Programming Language :: Python :: Implementation :: PyPy",
     ],

tox.ini

@@ -2,7 +2,7 @@
 minversion = 3.4.0
 envlist =
     docs, packaging, lint, vendoring,
-    py36, py37, py38, py39, pypy3
+    py36, py37, py38, py39, py310, pypy3
 
 [helpers]
 # Wrapper for calls to pip that make sure the version being used is the