Bump actions/upload-artifact from 4 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v4...v6)

---
updated-dependencies:
- dependency-name: actions/upload-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
           glob_root_file: true
           latexmk_shell_escape: true
           work_in_root_file_dir: true
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v6
         with:
           name: pdf
           path: "*/*.pdf"
@@ -37,7 +37,7 @@ jobs:
           sudo apt-get install pdf2svg
       - run: |
           make svgs
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v6
         with:
           name: svg
           path: "*/*.svg"
@@ -57,7 +57,7 @@ jobs:
           sudo sed -i '/disable ghostscript format types/,+6d' /etc/ImageMagick-6/policy.xml
       - run: |
           make gif
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v6
         with:
           name: gif
           path: "*/*.gif"
@@ -66,7 +66,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v6
-      - uses: actions/upload-artifact@v4
+      - uses: actions/upload-artifact@v6
         with:
           name: other
           path: |