Bump upload-artifact version.

Author: LarsAsplund

.github/workflows/coverage.yml

@@ -28,7 +28,7 @@ jobs:
     - name: Report coverage
       run: ./.github/run.sh coverage report -m --skip-covered
 
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: VUnit_coverage
         path: htmlcov

.github/workflows/docs.yml

@@ -32,7 +32,7 @@ jobs:
     - name: Build docs
       run: tox -e py311-docs -- --color
 
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: VUnit-site
         path: .tox/py311-docs/tmp/docsbuild/