deps: (deps): bump actions/download-artifact from 5 to 6

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

Author: dependabot[bot]

.github/workflows/nuget-release.yml

@@ -33,7 +33,7 @@ jobs:
       with:
         fetch-depth: 0
 
-    - uses: actions/download-artifact@v5
+    - uses: actions/download-artifact@v6
       with:
         path: './src'
         name: build

.github/workflows/release.yml

@@ -288,7 +288,7 @@ jobs:
         with:
           fetch-depth: 0
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           path: './src'
           name: build

.github/workflows/rl-secure.yml

@@ -54,7 +54,7 @@ jobs:
       - name: Setup NuGet
         uses: nuget/setup-nuget@v2
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           path: './src'
           name: build