Update workflow to newer actions.

Old versions were being deprecated.

.github/workflows/ci.yml

@@ -38,7 +38,7 @@ jobs:
           fetch-depth: 1
 
       - name: Install Java # for pyNeuroML
-        uses: actions/setup-java@v2
+        uses: actions/setup-java@v4
         with:
           distribution: 'adopt'
           java-version: '15'
@@ -53,7 +53,7 @@ jobs:
           sudo apt-get install -y --no-install-recommends wget make gcc libx11-dev libc6-dev xppaut
 
       - name: Install Singularity # to validate that the Docker image can be converted into a Singularity image
-        uses: eWaterCycle/setup-singularity@v5
+        uses: eWaterCycle/setup-singularity@v7
         with:
           singularity-version: 3.7.1
 
@@ -67,15 +67,15 @@ jobs:
         run: poetry run python -m flake8
 
       - name: Run the tests
-        uses: GabrielBB/xvfb-action@v1
+        uses: coactions/setup-xvfb@v1
         env:
           MPLBACKEND: PDF
           # BIOSIMULATORS_API_ENDPOINT: https://api.biosimulators.dev/  # uncomment to execute tests with the dev deployment
         with:
           run: poetry run python -m pytest tests/ --cov=./biosimulators_utils --cov-report=xml
 
       - name: Upload the coverage report to Codecov
-        uses: codecov/codecov-action@v2
+        uses: codecov/codecov-action@v4
         with:
           token: ${{ secrets.CODECOV_TOKEN }}
           flags: unittests