Update fixtures with Prettier formatting

src/fixtures/gatsby/blank.expected.js

@@ -1,2 +1,2 @@
 // Default Pages configuration for Gatsby
-module.exports = { pathPrefix: "/docs/" }
+module.exports = { pathPrefix: '/docs/' }

src/fixtures/gatsby/blank.js

@@ -1 +1 @@
-// This file is not read by the test suite
+// This file is not read by the test suite

src/fixtures/gatsby/default.expected.js

@@ -1,8 +1,8 @@
 module.exports = {
-  pathPrefix: "/docs/",
+  pathPrefix: '/docs/',
   siteMetadata: {
     title: `My Gatsby Site`,
-    siteUrl: `https://www.yourdomain.tld`,
+    siteUrl: `https://www.yourdomain.tld`
   },
-  plugins: [],
-}
+  plugins: []
+}

src/fixtures/gatsby/default.js

@@ -1,7 +1,7 @@
 module.exports = {
   siteMetadata: {
     title: `My Gatsby Site`,
-    siteUrl: `https://www.yourdomain.tld`,
+    siteUrl: `https://www.yourdomain.tld`
   },
-  plugins: [],
-}
+  plugins: []
+}