Bump download artifact version

Author: mysterymath

.github/workflows/verify.yml

@@ -71,7 +71,7 @@ jobs:
         run: |
           sudo apt-get install cmake ninja-build llvm
       - name: Download the compiler.
-        uses: actions/download-artifact@v2
+        uses: actions/download-artifact@v4
         with:
           name: compiler
       - name: Extract the compiler.