Bump actions/upload-artifact from 4 to 7 (#699)

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/joss.yml

@@ -23,7 +23,7 @@ jobs:
           GIT_SHA: $GITHUB_SHA
           JOURNAL: joss
       - name: Upload
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: paper
           path: paper/

.github/workflows/mpi.yml

@@ -184,7 +184,7 @@ jobs:
             pip install coverage
           fi
           NUMBA_NUM_THREADS=3 mpiexec $_mpiexec_args -n ${{ matrix.mpi-np }} python -m $COV_RUN pytest -p no:cacheprovider $COV_ARGS --timeout=600 --timeout_method=thread -s -vv -We tests_mpi;
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v7
         with:
           name: plots-${{matrix.mpi-np}}
           path: plots
@@ -220,7 +220,7 @@ jobs:
               done;
           done;
 
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v7
         with:
           name: anims
           path: plots/*-anim.gif