fix: contracts testing workflow

Author: jaybuidl

.github/workflows/contracts-testing.yml

@@ -61,7 +61,9 @@ jobs:
           ${{ runner.os }}-build-${{ secrets.CACHE_VERSION }}-${{ env.cache-name }}-
 
     - name: Install contracts dependencies
-      run: yarn workspace @kleros/kleros-v2-contracts install
+      run: |
+        yarn set version 4.5.1
+        yarn workspace @kleros/kleros-v2-contracts install
 
     - name: Install Foundry
       uses: foundry-rs/foundry-toolchain@8f1998e9878d786675189ef566a2e4bf24869773 # v1.2.0