Bump actions/upload-artifact from 4 to 7

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>

Author: dependabot[bot]

.github/workflows/prep_release.yml

@@ -60,14 +60,14 @@ jobs:
         cp target/viash.jar viash.jar
 
     - name: Upload JAR artifact
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: fat-jar
         path: viash.jar
         retention-days: 1
 
     - name: Upload release assets
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: release-assets
         path: |
@@ -122,7 +122,7 @@ jobs:
         ./viash --version
 
     - name: Upload native binary
-      uses: actions/upload-artifact@v4
+      uses: actions/upload-artifact@v7
       with:
         name: viash-${{ matrix.label }}
         path: viash