chore(deps): 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/draft-release.yml

@@ -31,12 +31,12 @@ jobs:
         run: |
           echo '${{ steps.srtool_build.outputs.json }}' | jq > ${{ matrix.runtime }}_srtool_output.json
       - name: Upload ${{ matrix.runtime }} srtool json
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: ${{ matrix.runtime }}-srtool-json
           path: ${{ matrix.runtime }}_srtool_output.json
       - name: Upload ${{ matrix.runtime }} runtime
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: ${{ matrix.runtime }}-runtime
           path: |
@@ -60,7 +60,7 @@ jobs:
           command: build
           args: --release --bin interbtc-parachain
       - name: Upload binary
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: interbtc
           path: target/release/interbtc-parachain