build: macos-13 is needed for older Pythons

Also:

- Update to latest versions of actions.

- Artifact upload/download had breaking changes.

.github/workflows/ci.yml

@@ -18,15 +18,15 @@ concurrency:
 jobs:
  tests:
  name: "Python ${{ matrix.python }} on ${{ matrix.os }}"
- runs-on: "${{ matrix.os }}"
+ runs-on: "${{ matrix.os }}-${{ matrix.os-version || 'latest' }}"
 
  strategy:
  fail-fast: false
  matrix:
  os:
- - ubuntu-latest
- - macos-latest
- - windows-latest
+ - ubuntu
+ - macos
+ - windows
  python:
  # When changing this list, be sure to check the [gh] list in
  # tox.ini so that tox will run properly.
@@ -36,13 +36,23 @@ jobs:
  - "3.10"
  - "3.11"
  - "3.12"
+ include:
+ - python: "3.7"
+ os: "macos"
+ os-version: "13"
+ - python: "3.8"
+ os: "macos"
+ os-version: "13"
+ - python: "3.9"
+ os: "macos"
+ os-version: "13"
 
  steps:
  - name: "Check out the repo"
- uses: "actions/checkout@v2"
+ uses: "actions/checkout@v4"
 
  - name: "Set up Python"
- uses: "actions/setup-python@v2"
+ uses: "actions/setup-python@v5"
  with:
  python-version: "${{ matrix.python }}"
 
@@ -56,9 +66,9 @@ jobs:
  python -m coverage debug data
 
  - name: "Upload coverage data"
- uses: actions/upload-artifact@v2
+ uses: actions/upload-artifact@v4
  with:
- name: covdata
+ name: covdata-${{ env.MATRIX_ID }}
  path: .coverage.*
 
  combine:
@@ -68,12 +78,12 @@ jobs:
 
  steps:
  - name: "Check out the repo"
- uses: "actions/checkout@v2"
+ uses: "actions/checkout@v4"
  with:
  fetch-depth: "0"
 
  - name: "Set up Python"
- uses: "actions/setup-python@v2"
+ uses: "actions/setup-python@v5"
  with:
  python-version: "3.8"
 
@@ -82,9 +92,10 @@ jobs:
  python -m pip install -r requirements.pip
 
  - name: "Download coverage data"
- uses: actions/download-artifact@v2
+ uses: actions/download-artifact@v4
  with:
- name: covdata
+ pattern: covdata-*
+ merge-multiple: true
 
  - name: "Combine and report"
  run: |