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](https://github.com/actions/upload-artifact/compare/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>

.github/workflows/build.yml

@@ -16,7 +16,7 @@ jobs:
       - uses: codecov/codecov-action@v5
         with:
           name: ${{ github.job }}
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           name: codecov debug results ${{ github.job }}
           path: "/tmp/codecov.*.gz"
@@ -36,7 +36,7 @@ jobs:
           cd znc-git-$date
           export CFGFLAGS="--with-gtest=$GITHUB_WORKSPACE/third_party/googletest/googletest --with-gmock=$GITHUB_WORKSPACE/third_party/googletest/googlemock --disable-swig"
           source $GITHUB_WORKSPACE/.github/build.sh
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           name: znc-tarball
           path: /tmp/znc-git*.tar.gz
@@ -61,7 +61,7 @@ jobs:
       - uses: codecov/codecov-action@v5
         with:
           name: ${{ github.job }}
-      - uses: actions/upload-artifact@v5
+      - uses: actions/upload-artifact@v6
         with:
           name: codecov debug results ${{ github.job }}
           path: "/tmp/codecov.*.gz"

.github/workflows/cifuzz.yml

@@ -20,7 +20,7 @@ jobs:
         dry-run: false
         language: c++
     - name: Upload Crash
-      uses: actions/upload-artifact@v5
+      uses: actions/upload-artifact@v6
       if: failure() && steps.build.outcome == 'success'
       with:
         name: artifacts