test: modernize some workflow stuff

Author: nedbat

.github/workflows/tests.yml

@@ -12,6 +12,9 @@ on:
     # week, Sundays at 6:00 UTC.
     - cron: "0 6 * * 0"
 
+permissions:
+  contents: read
+
 concurrency:
   group: "${{ github.workflow }}-${{ github.ref }}"
   cancel-in-progress: true
@@ -26,15 +29,15 @@ env:
 
 jobs:
   tests:
-    name: "Python ${{ matrix.python-version }} on ${{ matrix.os }}"
-    runs-on: "${{ matrix.os }}"
+    name: "${{ matrix.python-version }} on ${{ matrix.os }}"
+    runs-on: "${{ matrix.os }}-latest"
 
     strategy:
       matrix:
         os:
-          - ubuntu-latest
-          - macos-latest
-          - windows-latest
+          - ubuntu
+          - macos
+          - windows
         python-version:
           # When changing this list, be sure to check the [gh-actions] list in
           # tox.ini so that tox will run properly.
@@ -46,12 +49,13 @@ jobs:
 
     steps:
       - name: "Check out the repo"
-        uses: "actions/checkout@v2"
+        uses: "actions/checkout@v3"
 
       - name: "Set up Python"
-        uses: "actions/setup-python@v2"
+        uses: "actions/setup-python@v4"
         with:
           python-version: "${{ matrix.python-version }}"
+          allow-prereleases: true
 
       - name: "Install dependencies"
         run: |