chore(deps-dev): bump @vuepress/plugin-back-to-top from 1.6.0 to 1.7.0

Bumps [@vuepress/plugin-back-to-top](https://github.com/vuejs/vuepress/tree/HEAD/packages/@vuepress/plugin-back-to-top) from 1.6.0 to 1.7.0.
- [Release notes](https://github.com/vuejs/vuepress/releases)
- [Changelog](https://github.com/vuejs/vuepress/blob/master/CHANGELOG.md)
- [Commits](https://github.com/vuejs/vuepress/commits/v1.7.0/packages/@vuepress/plugin-back-to-top)

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

package.json

@@ -39,7 +39,7 @@
     "devDependencies": {
         "@babel/core": "^7.6.0",
         "@babel/preset-env": "^7.4.5",
-        "@vuepress/plugin-back-to-top": "1.6.0",
+        "@vuepress/plugin-back-to-top": "1.7.0",
         "@vuepress/plugin-google-analytics": "1.6.0",
         "@vuepress/plugin-pwa": "1.6.0",
         "art-template": "4.13.2",

yarn.lock

@@ -1228,10 +1228,10 @@
   dependencies:
     lodash.debounce "^4.0.8"
 
-"@vuepress/plugin-back-to-top@1.6.0":
-  version "1.6.0"
-  resolved "https://registry.yarnpkg.com/@vuepress/plugin-back-to-top/-/plugin-back-to-top-1.6.0.tgz#a10df98b7a4f57c627f72289cd0ab2ff0f075a1d"
-  integrity sha512-nJr/qlBcCN8vUyAb3nZPKqBS1DjfgZJquroOOd41CcLgsq3yAxmWLmxbLjg1MoBxk1Q8TrWz8qI7JRIw7W4aVw==
+"@vuepress/plugin-back-to-top@1.7.0":
+  version "1.7.0"
+  resolved "https://registry.yarnpkg.com/@vuepress/plugin-back-to-top/-/plugin-back-to-top-1.7.0.tgz#d4210ddf94a541b49ab72c4bbd820ceaa20ebb64"
+  integrity sha512-KaxhsbHgKMzAmjCOkmpUxNWfHCpWdyU2UT0tMe1cWTc/PLHSS1HYF4C9h1GM2g/zrVNsxerAU1DvJjToyD1lLA==
   dependencies:
     lodash.debounce "^4.0.8"