Bump @snowpack/plugin-webpack from 2.0.12 to 2.3.1 (#574)

Bumps [@snowpack/plugin-webpack](https://github.com/snowpackjs/snowpack/tree/HEAD/plugins/plugin-webpack) from 2.0.12 to 2.3.1.
- [Release notes](https://github.com/snowpackjs/snowpack/releases)
- [Changelog](https://github.com/snowpackjs/snowpack/blob/main/plugins/plugin-webpack/CHANGELOG.md)
- [Commits](https://github.com/snowpackjs/snowpack/commits/@snowpack/plugin-webpack@2.3.1/plugins/plugin-webpack)

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -44,7 +44,7 @@
     "@jest/types": "^26.6.2",
     "@snowpack/app-scripts-react": "^1.10.0",
     "@snowpack/plugin-postcss": "1.0.4",
-    "@snowpack/plugin-webpack": "2.0.12",
+    "@snowpack/plugin-webpack": "2.3.1",
     "@storybook/addon-actions": "^6.1.7",
     "@storybook/addon-essentials": "^6.1.7",
     "@storybook/addon-info": "^5.3.21",