Bump semver from 5.6.0 to 6.0.0 (#5451)

Bumps [semver](https://github.com/npm/node-semver) from 5.6.0 to 6.0.0.
- [Release notes](https://github.com/npm/node-semver/releases)
- [Changelog](https://github.com/npm/node-semver/blob/master/CHANGELOG.md)
- [Commits](https://github.com/npm/node-semver/compare/v5.6.0...v6.0.0)

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

package.json

@@ -37,7 +37,7 @@
     "parse": "2.2.1",
     "pg-promise": "8.6.4",
     "redis": "2.8.0",
-    "semver": "5.6.0",
+    "semver": "6.0.0",
     "tv4": "1.3.0",
     "uuid": "3.3.2",
     "winston": "2.4.4",