chore: change verify workflow to not use yarn on nested packages

Author: lukasbach

.github/workflows/verify.yml

@@ -19,9 +19,9 @@ jobs:
       - name: Custom React version
         run: |
           echo "enableImmutableInstalls: false" > ./.yarnrc.yml
-          yarn add react@${{ matrix.react }} -D
+          npm pkg set devDependencies.react ${{matrix.react}}
           cd packages/core
-          yarn add react@${{ matrix.react }} -D
+          npm pkg set devDependencies.react ${{matrix.react}}
           cd ../..
           cat ./.yarnrc.yml
           yarn