⬆️ Bump actions/upload-artifact from 4 to 7 (#180)

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v7)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '7'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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/cache.yml

@@ -41,13 +41,13 @@ jobs:
         run: |
           jb build lectures --path-output ./ -n -W --keep-going
       - name: Upload Execution Reports (HTML)
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         if: failure()
         with:
           name: execution-reports
           path: _build/html/reports
       - name: Upload "_build" folder (cache)
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: build-cache
           path: _build

.github/workflows/ci.yml

@@ -55,7 +55,7 @@ jobs:
       #     mkdir -p _build/html/_pdf
       #     cp -u _build/latex/*.pdf _build/html/_pdf
       # - name: Upload Execution Reports (LaTeX)
-      #   uses: actions/upload-artifact@v4
+      #   uses: actions/upload-artifact@v7
       #   if: failure()
       #   with:
       #     name: execution-reports
@@ -75,7 +75,7 @@ jobs:
         run: |
           jb build lectures --path-output ./ -n -W --keep-going
       - name: Upload Execution Reports (HTML)
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         if: failure()
         with:
           name: execution-reports

.github/workflows/publish.yml

@@ -117,7 +117,7 @@ jobs:
           publish_dir: _build/html/
           # cname: intro-cn.quantecon.org
       - name: Upload "_build" folder (publish)
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v7
         with:
           name: build-publish
           path: _build