build(deps-dev): bump next from 7.0.0-canary.16 to 7.0.0-canary.20 (#159)

Bumps [next](https://github.com/zeit/next.js) from 7.0.0-canary.16 to 7.0.0-canary.20.
- [Release notes](https://github.com/zeit/next.js/releases)
- [Commits](https://github.com/zeit/next.js/compare/7.0.0-canary.16...7.0.0-canary.20)

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

package.json

@@ -40,7 +40,7 @@
   "devDependencies": {
     "babel-eslint": "^9.0.0",
     "micro-dev": "^3.0.0",
-    "next": "^7.0.0-canary.16",
+    "next": "^7.0.0-canary.20",
     "react": "^16.5.1",
     "react-dom": "^16.5.1",
     "standard": "^12.0.1",