Migrate from MDX v0 to v1

MDX 1.0.0 (1) has been released including an official
migration guide for v0 to v1 (2).

The `@mdx-js/tag` package has been replaced with the `@mdx-js/react`
package. The new v1 pragma allows to use MDX with any renderer like
React, Vue or Preact.

References:
  (1) https://mdxjs.com/blog/v1
  (2) https://mdxjs.com/migrating/v1

GH-137

package.json

@@ -52,7 +52,6 @@
     "@babel/plugin-proposal-nullish-coalescing-operator": "7.4.3",
     "@babel/plugin-proposal-optional-chaining": "7.2.0",
     "@mdx-js/mdx": "1.0.14",
-    "@mdx-js/tag": "0.20.3",
     "@svgr/webpack": "4.2.0",
     "babel-eslint": "10.0.1",
     "babel-jest": "24.7.1",
@@ -90,6 +89,7 @@
     "webpack-bundle-analyzer": "3.3.2"
   },
   "dependencies": {
+    "@mdx-js/react": "1.0.6",
     "arctic-landscape": ">=0.1.0 <1.0.0",
     "arctic-ocean-fractal": ">=0.1.0 <1.0.0",
     "axios": "0.18.0",

src/components/templates/blog/BlogPost.jsx

@@ -9,7 +9,7 @@
 
 import React from "react";
 import MDXRenderer from "gatsby-mdx/mdx-renderer";
-import { MDXProvider } from "@mdx-js/tag";
+import { MDXProvider } from "@mdx-js/react";
 import { graphql } from "gatsby";
 
 import BaseLayout from "layouts/core/BaseLayout";

src/components/templates/docs/DocsPage.jsx

@@ -9,7 +9,7 @@
 
 import React from "react";
 import MDXRenderer from "gatsby-mdx/mdx-renderer";
-import { MDXProvider } from "@mdx-js/tag";
+import { MDXProvider } from "@mdx-js/react";
 import { graphql } from "gatsby";
 
 import { WaveFooter } from "atoms/core/vectors/divider";