Bump actions/upload-artifact from 5 to 6

Bumps [actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/upload-artifact/releases)
- [Commits](actions/upload-artifact@v5...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/cd.yml

@@ -51,7 +51,7 @@ jobs:
           # using this token rather than github.token due to `release not found` bug
           # https://github.com/pkgxdev/cli/issues/5252
           GH_TOKEN: ${{ secrets.GH_TOKEN }}
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           name: srcs
           path: ${{ env.FILENAME }}.tar.gz

.github/workflows/ci.ca-cert.yml

@@ -22,7 +22,7 @@ jobs:
       - run: apt-get update && apt-get install -y curl gcc perl make
       - uses: dtolnay/rust-toolchain@stable
       - run: cargo build --release
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           path: ./target/release/pkgx
           name: pkgx