ci: update actions

Author: trichter

.github/workflows/tests.yml

@@ -31,9 +31,9 @@ jobs:
       run:
         shell: bash -l {0}
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Setup conda
-        uses: conda-incubator/setup-miniconda@v3
+        uses: conda-incubator/setup-miniconda@v4
         with:
           python-version: ${{ matrix.python }}
           environment-file: .github/test_conda_env.yml
@@ -51,7 +51,7 @@ jobs:
           coverage combine
           coverage xml -o ../coverage.xml
       - name: upload coverage
-        uses: codecov/codecov-action@v4
+        uses: codecov/codecov-action@v6
         with:
           token: ${{ secrets.CODECOV_TOKEN }} # required
           fail_ci_if_error: true