Upgrade Eleventy from 2 to 3

[otegami]

ref: #92

Eleventy v3.0.0 fully supports ESM.

• ref: https://github.com/11ty/eleventy/releases/tag/v3.0.0

Additionally, using require("@11ty/eleventy") with Eleventy v3.0.0 results
in compatibility issues as follows. Therefore, this is an appropriate time to
migrate our configuration from CommonJS to ESM.

> [email protected] build:11ty
> eleventy --pathprefix=hotwire_ja

[11ty] Eleventy Error (CLI):
[11ty] 1. Error in your Eleventy config file '.eleventy.js'. (via EleventyConfigError)
[11ty] 2. `require("@11ty/eleventy")` is incompatible with Eleventy v3 and this version of Node. You have a few options:
[11ty]    1. (Easiest) Change the `require` to use a dynamic import inside of an asynchronous CommonJS configuration
[11ty]       callback, for example:
[11ty]
[11ty]       module.exports = async function {
[11ty]         const {EleventyRenderPlugin, EleventyI18nPlugin, EleventyHtmlBasePlugin} = await import("@11ty/eleventy");
[11ty]       }
[11ty]
[11ty]    2. (Easier) Update the JavaScript syntax in your configuration file from CommonJS to ESM (change `require`
[11ty]       to use `import` and rename the file to have an `.mjs` file extension).
[11ty]
[11ty]    3. (More work) Change your project to use ESM-first by adding `"type": "module"` to your package.json. Any
[11ty]       `.js` will need to be ported to use ESM syntax (or renamed to `.cjs`.)
[11ty]
[11ty]    4. (Short term workaround) Use the --experimental-require-module flag to enable this behavior. Read
[11ty]       more: https://nodejs.org/api/modules.html#loading-ecmascript-modules-using-require It is possible that the
[11ty]       newest version of Node has this enabled by default—you can try upgrading your version of Node.js.
ERROR: "build:11ty" exited with 1.

[akira888]

おお、11tyのUPGRADE！

[otegami]

@akira888
11tyを試しにあげてみました。既存の設定を壊さないで上げてみたので良かったらレビューをお願いします 🙏
差分が多いですが、主にpackage.jsonの変更なので実質的にはそんなに変更を入れてないですmm

[akira888]

Build時に SASSについて とやかく言われているのを見かけてしまいましたがｗ
11ty自体の version up は問題なさそうでした！
早めの追随ありがとうございます！

[akira888]

SassはもうひとつのPRでご対応いただいていたのですね
ありがとうございます！

[otegami]

レビューありがとうございます。マージします！