chore(deps-dev): bump @vuepress/plugin-back-to-top from 1.3.0 to 1.3.1

Bumps [@vuepress/plugin-back-to-top](https://github.com/vuejs/vuepress/tree/HEAD/packages/@vuepress/plugin-back-to-top) from 1.3.0 to 1.3.1.
- [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/v1.3.1/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": "1.3.0",
+        "@vuepress/plugin-back-to-top": "1.3.1",
         "@vuepress/plugin-google-analytics": "1.3.0",
         "@vuepress/plugin-pwa": "1.3.0",
         "art-template": "4.13.2",

yarn.lock

@@ -1133,10 +1133,10 @@
   dependencies:
     lodash.debounce "^4.0.8"
 
-"@vuepress/plugin-back-to-top@1.3.0":
-  version "1.3.0"
-  resolved "https://registry.yarnpkg.com/@vuepress/plugin-back-to-top/-/plugin-back-to-top-1.3.0.tgz#0193858287d6c18b30e31c4730ecaecef7c8d7b5"
-  integrity sha512-YuJEYaxPRAJScoqiq4uEcqdVt+vBOpdTDhepxtmN0vDRatvOqwJctwi5xqHcII2ziB7ddhOsibk8fhYwc/42ww==
+"@vuepress/plugin-back-to-top@1.3.1":
+  version "1.3.1"
+  resolved "https://registry.yarnpkg.com/@vuepress/plugin-back-to-top/-/plugin-back-to-top-1.3.1.tgz#51fbb043845b46a66e85f66ae099041c76f08abc"
+  integrity sha512-vjfYqSnlZy7Z1Hmre7rw3crtUk9nVUJw+fG0CKp5VXLdBnzrACZznxrFw1BhuzqnV9UT3vq6n8MTlcbpq2Xs8g==
   dependencies:
     lodash.debounce "^4.0.8"