Set up 3.11 in metadata and GitHub Actions.

.github/workflows/ci.yml

@@ -51,12 +51,13 @@ jobs:
           - "3.8"
           - "3.9"
           - "3.10"
+          - "3.11"
         include:
           # On macOS don't bother with 3.8, just to get faster builds.
           - os: macos-latest
             python-version: "3.9"
           - os: macos-latest
-            python-version: "3.10"
+            python-version: "3.11"
           # We only support PyPy on Linux at the moment.
           - os: ubuntu-latest
             python-version: "pypy-3.8"
@@ -174,7 +175,7 @@ jobs:
           # 22.04 has some issue with Tor at the moment:
           # https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3943
           - os: ubuntu-20.04
-            python-version: "3.9"
+            python-version: "3.11"
             force-foolscap: false
     steps:
 

newsfragments/3982.feature

@@ -0,0 +1 @@
+Added support for Python 3.11.

setup.py

@@ -55,7 +55,9 @@ install_requires = [
     # * foolscap >= 0.12.6 has an i2p.sam_endpoint() that takes kwargs
     # * foolscap 0.13.2 drops i2p support completely
     # * foolscap >= 21.7 is necessary for Python 3 with i2p support.
+    # * foolscap >= 23.3 is necessary for Python 3.11.
     "foolscap >= 21.7.0",
+    "foolscap >= 23.3.0; python_version > '3.10'",
 
     # * cryptography 2.6 introduced some ed25519 APIs we rely on.  Note that
     #   Twisted[conch] also depends on cryptography and Twisted[tls]
@@ -380,8 +382,8 @@ setup(name="tahoe-lafs", # also set in __init__.py
       package_dir = {'':'src'},
       packages=find_packages('src') + ['allmydata.test.plugins'],
       classifiers=trove_classifiers,
-      # We support Python 3.8 or later. 3.11 is not supported yet.
-      python_requires=">=3.8, <3.11",
+      # We support Python 3.8 or later
+      python_requires=">=3.8",
       install_requires=install_requires,
       extras_require={
           # Duplicate the Twisted pywin32 dependency here.  See