npm -> yarn

Author: cprayer

.github/workflows/gh-pages-publish.yaml

@@ -23,9 +23,10 @@ jobs:
           restore-keys: |
             ${{ runner.os }}-node-
 
-      - run: npm install
+      - run: npm install -g yarn
       - run: npm install -g gatsby-cli@2.12.34
-      - run: npm run build
+      - run: yarn install
+      - run: yarn run build
 
       - name: Deploy
         uses: peaceiris/actions-gh-pages@v4