Change naming of sphinx test

.github/workflows/test-sphinx.yml

@@ -14,8 +14,7 @@ jobs:
       python-version: '3.10'
     strategy:
       matrix:
-        tasks: [ 'sphinx' ]
-        sphinx-version: [ '5.3.0', '6.2.1', '7.*' ]
+        sphinx: [ 'sphinx==5.3.0', 'sphinx==6.2.1', 'sphinx==7.*' ]
 
     steps:
     - uses: actions/checkout@v4
@@ -31,7 +30,7 @@ jobs:
         python -m pip install --upgrade pip
         pip install -r requirements.txt
         pip install -r docs/requirements.txt
-        pip install "sphinx==${{ matrix.sphinx-version }}"
+        pip install "${{ matrix.sphinx-version }}"
 
     - name: Tests
       run: |