Bump actions/upload-artifact from 4 to 5

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 5.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v5)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '5'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

.github/workflows/pytest.yml

@@ -45,19 +45,19 @@ jobs:
         CODECOV_TOKEN: ${{ secrets.CODECOV_TOKEN }}
     - name: Save PFSS plot as artifcat
       if: always()
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v5
       with:
         name: ${{ matrix.python-version }}-pfss-plot-artifact
         path: "/home/runner/work/solarmach/solarmach/tmp_solarmach_pfss.png"
     - name: Save standard plot as artifcat
       if: always()
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v5
       with:
         name: ${{ matrix.python-version }}-standard-plot-artifact
         path: "/home/runner/work/solarmach/solarmach/tmp_solarmach.png"
     - name: Save pytest-mpl report as artifcat
       if: always()
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v5
       with:
         name: ${{ matrix.python-version }}-pytest-mpl-report-artifact
         path: "/home/runner/work/solarmach/solarmach/report/"