chore: switch from npm to yarn

.gitea/workflows/deploy.yaml

@@ -9,17 +9,17 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v3
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 18.x
+      - run: corepack enable
+      - run: yarn install --frozen-lockfile
       - uses: purcell/setup-emacs@master
         with:
           version: 29.1
       - name: "Export org to md"
         run: emacs -Q --script export.el
-      - uses: actions/setup-node@v3
-        with:
-          node-version: 18.x
-      - run: npm ci
-      - name: "Build"
-        run: npm run docs:build
+      - run: yarn docs:build
       - name: "Deploy"
         uses: appleboy/scp-action@v0.1.7
         with: