Drop Python 3.8 support (#642)

Upstream dependencies (e.g. numpy, scipy) have now dropped Python 3.8
support in latest releases.

Add Python 3.11 support.

See also https://dials.github.io/kb/proposals/dc3

---------

Co-authored-by: Nicholas Devenish <ndevenish@gmail.com>

.azure-pipelines/azure-pipelines.yml

@@ -14,11 +14,11 @@ stages:
     steps:
       - checkout: none
 
-      # Use Python >=3.8 for syntax validation
+      # Use Python >=3.9 for syntax validation
       - task: UsePythonVersion@0
         displayName: Set up python
         inputs:
-          versionSpec: 3.8
+          versionSpec: 3.9
 
       # Run syntax validation on a shallow clone
       - bash: |
@@ -78,7 +78,7 @@ stages:
         vmImage: ubuntu-20.04
       timeoutInMinutes: 60
       variables:
-        PYTHON_VERSION: 3.8
+        PYTHON_VERSION: 3.9
       steps:
       - template: unix-build.yml
 
@@ -88,10 +88,10 @@ stages:
         vmImage: ubuntu-20.04
       strategy:
         matrix:
-          python38:
-            PYTHON_VERSION: 3.8
           python39:
             PYTHON_VERSION: 3.9
+          python311:
+            PYTHON_VERSION: 3.11
       timeoutInMinutes: 60
       steps:
       - template: unix-build.yml
@@ -101,10 +101,10 @@ stages:
         vmImage: macOS-latest
       strategy:
         matrix:
-          python38:
-            PYTHON_VERSION: 3.8
           python39:
             PYTHON_VERSION: 3.9
+          python311:
+            PYTHON_VERSION: 3.11
       timeoutInMinutes: 60
       steps:
       - template: unix-build.yml
@@ -114,8 +114,10 @@ stages:
         vmImage: windows-2019
       strategy:
         matrix:
-          python38:
-            PYTHON_VERSION: 3.8
+          python39:
+            PYTHON_VERSION: 3.9
+          python311:
+            PYTHON_VERSION: 3.11
       timeoutInMinutes: 20
       steps:
       - template: windows-build.yml

.azure-pipelines/bootstrap.py

@@ -847,7 +847,7 @@ def run():
         "--python",
         help="Install this minor version of Python (default: %(default)s)",
         default="3.9",
-        choices=("3.8", "3.9", "3.10"),
+        choices=("3.9", "3.10", "3.11"),
     )
     parser.add_argument(
         "--branch",

newsfragments/642.misc

@@ -0,0 +1 @@
+Drop Python 3.8 support in line with https://dials.github.io/kb/proposals/dc3. Add Python 3.11 support.

setup.cfg

@@ -8,8 +8,9 @@ classifiers =
     Operating System :: Microsoft :: Windows
     Operating System :: POSIX :: Linux
     Programming Language :: Python :: 3
-    Programming Language :: Python :: 3.8
     Programming Language :: Python :: 3.9
+    Programming Language :: Python :: 3.10
+    Programming Language :: Python :: 3.11
 
 [flake8]
 # Black disagrees with flake8 on a few points. Ignore those.