build(deps): bump actions/upload-artifact in /.github/workflows

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v3...v4)

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

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

.github/workflows/docs.yml

@@ -22,7 +22,7 @@ jobs:
         # Upload the doxygen artifacts on pull requests to help reviewers easily
         # view changes.
         if: ${{ github.event_name == 'pull_request' }}
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
             name: s2n-tls-doxygen
             path: |

.github/workflows/proof_ci.yaml

@@ -226,7 +226,7 @@ jobs:
             && mv $FINAL_REPORT_DIR/${{ steps.artifact.outputs.name }}.zip .
       - name: Upload zip artifact of CBMC proof results to GitHub Actions
         if: ${{ env.REPO_VISIBILITY == 'public' }}
-        uses: actions/upload-artifact@v3
+        uses: actions/upload-artifact@v4
         with:
           name: ${{ steps.artifact.outputs.name }}
           path: ${{ steps.artifact.outputs.name }}.zip