Bump highcharts from 6.1.0 to 7.2.2

Bumps [highcharts](https://github.com/highcharts/highcharts-dist) from 6.1.0 to 7.2.2.
- [Release notes](https://github.com/highcharts/highcharts-dist/releases)
- [Commits](highcharts/highcharts-dist@v6.1.0...v7.2.2)

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

Author: dependabot[bot]

package.json

@@ -64,7 +64,7 @@
         "foundation-sites": "git+https://github.com/steemit/foundation-sites.git#e8e32c715bbc4c822b80b555345f61337269ca78",
         "fs": "^0.0.1-security",
         "git-rev-sync": "1.9.1",
-        "highcharts": "6.1.0",
+        "highcharts": "7.2.2",
         "hjson": "^3.2.1",
         "humanize-number": "0.0.2",
         "imports-loader": "0.7.1",

yarn.lock

@@ -5299,10 +5299,10 @@ hide-powered-by@1.1.0:
   resolved "https://registry.yarnpkg.com/hide-powered-by/-/hide-powered-by-1.1.0.tgz#be3ea9cab4bdb16f8744be873755ca663383fa7a"
   integrity sha512-Io1zA2yOA1YJslkr+AJlWSf2yWFkKjvkcL9Ni1XSUqnGLr/qRQe2UI3Cn/J9MsJht7yEVCe0SscY1HgVMujbgg==
 
-highcharts@6.1.0:
-  version "6.1.0"
-  resolved "https://registry.yarnpkg.com/highcharts/-/highcharts-6.1.0.tgz#115a6ee10ad36a53d9913f1030c6d46da16c7cb5"
-  integrity sha512-YZotALyZD1xJixB8pNOKqBpmxV/NrOpMHQ3l7/CMB1hn5U7KRSviaeyv8/1MT7/rTgEFPOW85mdaFKFr2EfeAw==
+highcharts@7.2.2:
+  version "7.2.2"
+  resolved "https://registry.yarnpkg.com/highcharts/-/highcharts-7.2.2.tgz#94d6bae545d7f0fbf49615b28640f5fdbf99d11e"
+  integrity sha512-jRKujQuPKHLgGQd2sByBI9K5m56CInm2augVZnBYqdmyoU88hcI62uuAXHvxC3FW8YY0FJ74A1uw6sxrcmcmvg==
 
 highcharts@^4.2.3:
   version "4.2.7"