build(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/build.yml

@@ -121,7 +121,7 @@ jobs:
 
       - name: Archive artifacts
         if: matrix.compiler == 'ldc'
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: soulfind-${{ matrix.os }}
           path: |

.github/workflows/container.yml

@@ -38,7 +38,7 @@ jobs:
           docker push $IMAGE_NAME:latest-${{ matrix.arch }}
 
       - name: Upload image artifact
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: soulfind-image-${{ matrix.arch }}
           path: soulfind-image-${{ matrix.arch }}.tar

.github/workflows/libraries.yml

@@ -36,7 +36,7 @@ jobs:
           }
 
       - name: Upload artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         with:
           name: libs-${{ matrix.arch }}
           path: lib/*.lib