chore(deps): bump actions/download-artifact from 3 to 4

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 3 to 4.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v3...v4)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/docs.yml

@@ -80,7 +80,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Download artifact
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: metadata
           path: doc/docs/reference

.github/workflows/main.yml

@@ -165,7 +165,7 @@ jobs:
         run: sed -i 's/<ReferenceOutputAssembly>false<\/ReferenceOutputAssembly>/<ReferenceOutputAssembly>true<\/ReferenceOutputAssembly>/g' *.csproj
 
       - name: Get test coverages
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: Test results 2020
           path: Tests
@@ -174,7 +174,7 @@ jobs:
       # Run this as late as possible, to give time for publish job to finish and upload
       - name: Get version
         continue-on-error: true
-        uses: actions/download-artifact@v3
+        uses: actions/download-artifact@v4
         with:
           name: SemanticVersion
           path: SemanticVersion