Bump actions/upload-artifact from 6 to 7

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 6 to 7.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v6...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>

Author: dependabot[bot]

.github/workflows/docsite.yml

@@ -17,7 +17,7 @@ jobs:
       - name: Build
         run: mkdocs build -s
       - name: Upload artifact
-        uses: actions/upload-artifact@v6
+        uses: actions/upload-artifact@v7
         with:
           name: site
           path: site

.github/workflows/release-asset.yml

@@ -72,7 +72,7 @@ jobs:
           zip -jr elixir-ls-v${{ steps.version.outputs.version }}.zip ./release
 
       - name: Upload build artifact
-        uses: actions/upload-artifact@v6
+        uses: actions/upload-artifact@v7
         with:
           name: elixir-ls-${{ steps.version.outputs.version }}
           path: elixir-ls-v${{ steps.version.outputs.version }}.zip