BREAKING: v3

[LekoArts]

Major update for all themes!

This PR updates all themes to the latest and greatest of each respective package. So support for latest version of Gatsby (v3) and i18n libraries.

Breaking Changes

Before upgrading to the new versions you'll want to update your core gatsby version to v3 (+ all plugins) as well: Migrating from v2 to v3 documentation

• Requires Gatsby v3
• Requires React 17
• Requires Node >=12.13.0
• All Gatsby related plugins/packages were updated a major, too

Please look at the starters folder for working examples with the new setup!

gatsby-theme-blog / gatsby-theme-blog-core / gatsby-theme-blog-darkmode

• gatsby-image was replaced with gatsby-plugin-image
• The mdx option from gatsby-theme-blog was removed (use mdxOtherwiseConfigured instead)
• Updated Theme UI to 0.7 Theme UI's migration guide

gatsby-theme-notes

• Removed gatsby-plugin-compile-es6-packages (not needed anymore)
• The mdx option from gatsby-theme-blog was removed (use mdxOtherwiseConfigured instead)
• Updated Theme UI to 0.7 Theme UI's migration guide

gatsby-theme-ui-preset

• Removed all dependencies (theme-ui needs to be installed to have the preset working)

gatsby-theme-i18n

• Made gatsby-plugin-react-helmet and react-helmet peerDependencies. You'll need to install them yourself now

gatsby-theme-i18n-lingui

• Updated to lingui v3
• Installing @lingui/core is now required, too

Non-Breaking Improvements

• Replaced import React from 'react' with import * as React from 'react'
• Replaced anonymous default exports with named default exports
• Added TS types to gatsby-theme-i18n
• Improved READMEs

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Fixes #106

[LekoArts]

Published canary version to try out:

 - gatsby-theme-blog-core@gatsby-v3
 - gatsby-theme-blog-darkmode@gatsby-v3
 - gatsby-theme-blog@gatsby-v3
 - gatsby-theme-i18n-lingui@gatsby-v3
 - gatsby-theme-i18n-react-i18next@gatsby-v3
 - gatsby-theme-i18n-react-intl@gatsby-v3
 - gatsby-theme-i18n@gatsby-v3
 - gatsby-theme-notes@gatsby-v3
 - gatsby-theme-ui-preset@gatsby-v3