Bump gatsby-plugin-offline from 3.0.6 to 3.0.8

Bumps [gatsby-plugin-offline](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-offline) from 3.0.6 to 3.0.8.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-offline/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-offline@3.0.8/packages/gatsby-plugin-offline)

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

Author: dependabot-preview[bot]

package.json

@@ -9,7 +9,7 @@
     "gatsby": "^2.15.19",
     "gatsby-image": "^2.2.19",
     "gatsby-plugin-manifest": "^2.2.18",
-    "gatsby-plugin-offline": "^3.0.6",
+    "gatsby-plugin-offline": "^3.0.8",
     "gatsby-plugin-postcss": "^2.1.8",
     "gatsby-plugin-react-helmet": "^3.1.7",
     "gatsby-plugin-sharp": "^2.2.22",

yarn.lock

@@ -5180,10 +5180,10 @@ gatsby-plugin-manifest@^2.2.18:
     semver "^5.7.1"
     sharp "^0.23.0"
 
-gatsby-plugin-offline@^3.0.6:
-  version "3.0.6"
-  resolved "https://registry.yarnpkg.com/gatsby-plugin-offline/-/gatsby-plugin-offline-3.0.6.tgz#254c75d696195fa37bf3ab6d744611df0d372815"
-  integrity sha512-pqGw/u3AWiBg9WX4VLhhv3gOrKnGnUXrqYNxQ3PPzURjX5vfsrrpL1i4fYEW4TAX1dbbJllkmN9ncde6TJF9Fw==
+gatsby-plugin-offline@^3.0.8:
+  version "3.0.8"
+  resolved "https://registry.yarnpkg.com/gatsby-plugin-offline/-/gatsby-plugin-offline-3.0.8.tgz#b2a78402810e0fbd98fb674f912172bce420438e"
+  integrity sha512-p6JDT9WTx/yUyKg+P3lwkTyr0mDB7iF9whLzHbgaeilx8jmRCVdrTYOs13FUERxxcmdtiX0s1yh/6isIs/upkg==
   dependencies:
     "@babel/runtime" "^7.6.0"
     cheerio "^1.0.0-rc.3"