chore(ci): Use node 12 on Size Check job. (#4162)

Author: onurtemizkan

.github/workflows/build.yml

@@ -102,6 +102,8 @@ jobs:
         uses: actions/checkout@v2
       - name: Set up Node
         uses: actions/setup-node@v1
+        with:
+          node-version: '12'
       - name: Check dependency cache
         uses: actions/cache@v2
         with: