Retrieve Node.js version from package.json instead of from .nvmrc

Signed-off-by: Sora Morimoto <sora@morimoto.io>

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: .nvmrc
-          check-latest: true
+          node-version-file: package.json
       - run: npm ci
       - run: npm run lint
+      - run: npm run build

.github/workflows/deploy.yml

@@ -26,8 +26,7 @@ jobs:
       - uses: actions/checkout@v4
       - uses: actions/setup-node@v4
         with:
-          node-version-file: .nvmrc
-          check-latest: true
+          node-version-file: package.json
       - run: npm ci
       - run: npm run build
       - uses: actions/configure-pages@v5

README.md

@@ -36,7 +36,7 @@ This website is intended as a content website. While it is a landing page for th
 
 ## Local development
 
-The website is built using [11ty](https://www.11ty.dev/) and requires a relatively up-to-date version of Node.js - preferably the version in [.nvmrc](./.nvmrc).
+The website is built using [11ty](https://www.11ty.dev/) and requires a relatively up-to-date version of Node.js - preferably the version in [package.json](./package.json).
 
 ```sh
 npm ci    # install dependencies from package-lock.json