Update upload-artifact to v4

Author: esilvia

.github/workflows/pdf.yml

@@ -28,11 +28,11 @@ jobs:
     - name: Spelling
       run: |
         make spelling
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: PDF
         path: build/latex/LAS.pdf
-    - uses: actions/upload-artifact@v3
+    - uses: actions/upload-artifact@v4
       with:
         name: Misspelled
         path: build/spelling/output.txt