Fix Anchor CI — use Solana CLI 3.1.8 (matches local toolchain)

Author: rocketiotemp

.github/workflows/test.yml

@@ -17,7 +17,7 @@ jobs:
           node-version: 22
       - name: Install Solana CLI
         run: |
-          sh -c "$(curl -sSfL https://release.anza.xyz/v2.1.21/install)"
+          sh -c "$(curl -sSfL https://release.anza.xyz/v3.1.8/install)"
           echo "$HOME/.local/share/solana/install/active_release/bin" >> $GITHUB_PATH
       - name: Install system dependencies
         run: sudo apt-get update && sudo apt-get install -y libudev-dev pkg-config