Bump gatsby-plugin-manifest from 2.2.18 to 2.2.20

Bumps [gatsby-plugin-manifest](https://github.com/gatsbyjs/gatsby/tree/HEAD/packages/gatsby-plugin-manifest) from 2.2.18 to 2.2.20.
- [Release notes](https://github.com/gatsbyjs/gatsby/releases)
- [Changelog](https://github.com/gatsbyjs/gatsby/blob/master/packages/gatsby-plugin-manifest/CHANGELOG.md)
- [Commits](https://github.com/gatsbyjs/gatsby/commits/gatsby-plugin-manifest@2.2.20/packages/gatsby-plugin-manifest)

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

Author: dependabot-preview[bot]

package.json

@@ -8,7 +8,7 @@
     "classnames": "^2.2.6",
     "gatsby": "^2.15.26",
     "gatsby-image": "^2.2.23",
-    "gatsby-plugin-manifest": "^2.2.18",
+    "gatsby-plugin-manifest": "^2.2.20",
     "gatsby-plugin-offline": "^3.0.11",
     "gatsby-plugin-postcss": "^2.1.10",
     "gatsby-plugin-react-helmet": "^3.1.8",

yarn.lock

@@ -5162,15 +5162,15 @@ gatsby-page-utils@^0.0.21:
     micromatch "^3.1.10"
     slash "^3.0.0"
 
-gatsby-plugin-manifest@^2.2.18:
-  version "2.2.18"
-  resolved "https://registry.yarnpkg.com/gatsby-plugin-manifest/-/gatsby-plugin-manifest-2.2.18.tgz#96bea26e35a8d74ebb74dff8c5c1ae85e7b0c556"
-  integrity sha512-velK1ApsQ/mEUABwmduMHVZISll4q9bJMtW1tOp+qbNUfJUFl2u4x6Ya36z8mxROX0mIKPAhYMAfhWq209rbcg==
+gatsby-plugin-manifest@^2.2.20:
+  version "2.2.20"
+  resolved "https://registry.yarnpkg.com/gatsby-plugin-manifest/-/gatsby-plugin-manifest-2.2.20.tgz#67fa1d6335846097364c2eceece5a4bdc326706e"
+  integrity sha512-VWDLZgOrVxQkEk6zjbvRv6lKvvrzLh9n385WisDGiU6X0cp58cpHdqJSTOEanqxbLW+/DX1M29RHLznYriS7Iw==
   dependencies:
-    "@babel/runtime" "^7.6.0"
-    gatsby-core-utils "^1.0.10"
+    "@babel/runtime" "^7.6.2"
+    gatsby-core-utils "^1.0.12"
     semver "^5.7.1"
-    sharp "^0.23.0"
+    sharp "^0.23.1"
 
 gatsby-plugin-offline@^3.0.11:
   version "3.0.11"