Update dependencies

Refs: #20

package.json

@@ -10,16 +10,16 @@
     "@material-ui/styles": "^4.10.0",
     "@svgr/webpack": "^5.4.0",
     "classnames": "^2.2.6",
-    "gatsby": "^2.23.3",
-    "gatsby-cli": "^2.12.45",
-    "gatsby-image": "^2.4.7",
-    "gatsby-plugin-manifest": "^2.4.11",
+    "gatsby": "^2.23.11",
+    "gatsby-cli": "^2.12.51",
+    "gatsby-image": "^2.4.9",
+    "gatsby-plugin-manifest": "^2.4.14",
     "gatsby-plugin-material-ui": "^2.1.9",
-    "gatsby-plugin-offline": "^3.2.9",
-    "gatsby-plugin-react-helmet": "^3.3.4",
-    "gatsby-plugin-sharp": "^2.6.11",
-    "gatsby-source-filesystem": "^2.3.11",
-    "gatsby-transformer-sharp": "^2.5.5",
+    "gatsby-plugin-offline": "^3.2.13",
+    "gatsby-plugin-react-helmet": "^3.3.6",
+    "gatsby-plugin-sharp": "^2.6.14",
+    "gatsby-source-filesystem": "^2.3.14",
+    "gatsby-transformer-sharp": "^2.5.7",
     "prop-types": "^15.7.2",
     "react": "^16.12.0",
     "react-countdown": "^2.2.1",
@@ -29,7 +29,7 @@
     "svgo-loader": "^2.2.1"
   },
   "devDependencies": {
-    "eslint": "^7.2.0",
+    "eslint": "^7.3.1",
     "eslint-plugin-react": "^7.20.0",
     "eslint-plugin-react-hooks": "^4.0.4",
     "husky": "^4.2.5",