Use coveralls github action

Because the command-line coveralls tool pins coverage < 7.0, which
doesn't work well on Python 3.12.

Also update all the GitHub actions to the latest versions and tweak YAML
formatting so all the shell commands are aligned.

.github/workflows/build.yml

@@ -29,15 +29,15 @@ jobs:
 
     steps:
       - name: Git clone
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: "${{ matrix.python-version }}"
 
       - name: Pip cache
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: ~/.cache/pip
           key: ${{ runner.os }}-pip-${{ matrix.python-version }}-${{ hashFiles('setup.py') }}
@@ -49,23 +49,24 @@ jobs:
         run: |
           python -m pip install -U pip
           python -m pip install -U setuptools wheel
-          python -m pip install -U pytest coverage coveralls
+          python -m pip install -U pytest coverage
           python -m pip install -e .
 
       - name: Run tests
-        run: coverage run -m pytest tests
+        run: |
+          coverage run -m pytest tests
 
       - name: Check test coverage
-        run: coverage report -m --fail-under=${{ (matrix.python-version == 'pypy-3.10') && 99 || 100 }}
+        run: |
+          coverage report -m --fail-under=${{ (matrix.python-version == 'pypy-3.10') && 99 || 100 }}
+          coverage xml
         # pypy3.10 thinks utils.py has one uncovered branch (140 -> 133), which
         # I think is just pypy's optimizer being too smart for coverage.py.
 
       - name: Report to coveralls
-        run: coveralls
-        continue-on-error: true
-        env:
-          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
-          COVERALLS_SERVICE_NAME: github
+        uses: coverallsapp/github-action@v2
+        with:
+          file: coverage.xml
 
   lint:
     name: ${{ matrix.toxenv }}
@@ -82,15 +83,15 @@ jobs:
 
     steps:
       - name: Git clone
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
 
       - name: Set up Python ${{ env.default_python || '3.9' }}
-        uses: actions/setup-python@v2
+        uses: actions/setup-python@v4
         with:
           python-version: "${{ env.default_python || '3.9' }}"
 
       - name: Pip cache
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         with:
           path: ~/.cache/pip
           key: ${{ runner.os }}-pip-${{ matrix.toxenv }}-${{ hashFiles('tox.ini') }}
@@ -105,4 +106,5 @@ jobs:
           python -m pip install -U tox
 
       - name: Run ${{ matrix.toxenv }}
-        run: python -m tox -e ${{ matrix.toxenv }}
+        run: |
+          python -m tox -e ${{ matrix.toxenv }}