Use Node.js v20.19 in "Publish Addon Docs" (ember-learn#1677)

Author: SergeAstapov

.github/workflows/addon-docs.yml

@@ -37,7 +37,7 @@ jobs:
       - uses: actions/setup-node@v4
         if: env.SHORT_CIRCUIT == 'false'
         with:
-          node-version: 18
+          node-version: 20.19.x
           cache: pnpm
       - name: Install Dependencies
         if: env.SHORT_CIRCUIT == 'false'