Bump actions/download-artifact from 5 to 6 (#22225)

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](https://github.com/actions/download-artifact/compare/v5...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

.github/workflows/linux.yaml

@@ -98,7 +98,7 @@ jobs:
           maven-version: 3.8.8
           cache: gradle
       - name: Download build artifact
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: artifact
       - name: Run Ensures Script

.github/workflows/openapi-generator.yaml

@@ -99,7 +99,7 @@ jobs:
           java-version: 11
           distribution: 'temurin'
       - name: Download openapi-generator-cli.jar artifact
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: openapi-generator-cli.jar
           path: modules/openapi-generator-cli/target
@@ -138,7 +138,7 @@ jobs:
           java-version: 11
           distribution: 'temurin'
       - name: Download openapi-generator-cli.jar artifact
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: openapi-generator-cli.jar
           path: modules/openapi-generator-cli/target