Build: npm -> yarn 으로 변경하면서 github workflow 수정

Author: gitgitWi

.github/workflows/deploy.yml

@@ -22,14 +22,14 @@ jobs:
         uses: actions/setup-node@v2
         with:
           node-version: ${{ matrix.node-version }}
-          cache: "npm"
+          cache: "yarn"
 
       - name: Install Packages
-        run: npm ci
+        run: yarn install --frozen-lockfile
 
       - name: Build 🔧
-        run: npm run build
-      - run: npm run export
+        run: yarn build
+      - run: yarn run export
       - run: touch ./out/.nojekyll
 
       - name: Deploy