chore(deps): update actions/upload-artifact action to v6 (sveltejs#15057)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/ci.yml

@@ -87,7 +87,7 @@ jobs:
         run: find packages -type d -name test-results -not -empty | tar -czf test-results.tar.gz --files-from=-
       - name: Upload test results
         if: failure()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           retention-days: 3
           name: test-failure-${{ github.run_id }}-${{ matrix.os }}-${{ matrix.node-version }}-${{ matrix.e2e-browser }}
@@ -145,7 +145,7 @@ jobs:
         run: find packages -type d -name test-results -not -empty | tar -czf test-results-cross-platform-${{ matrix.mode }}.tar.gz --files-from=-
       - name: Upload test results
         if: failure()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           retention-days: 3
           name: test-failure-cross-platform-${{ matrix.mode }}-${{ github.run_id }}-${{ matrix.os }}-${{ matrix.node-version }}-${{ matrix.e2e-browser }}
@@ -179,7 +179,7 @@ jobs:
         run: find packages -type d -name test-results -not -empty | tar -czf test-results-server-side-route-resolution-${{ matrix.mode }}.tar.gz --files-from=-
       - name: Upload test results
         if: failure()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           retention-days: 3
           name: test-failure-server-side-route-resolution-${{ matrix.mode }}-${{ github.run_id }}
@@ -213,7 +213,7 @@ jobs:
         run: find packages -type d -name test-results -not -empty | tar -czf test-results-svelte-async-${{ matrix.mode }}.tar.gz --files-from=-
       - name: Upload test results
         if: failure()
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           retention-days: 3
           name: test-failure-svelte-async-${{ matrix.mode }}-${{ github.run_id }}