fix: update dependency dotenv to v8 (#17027)

Author: renovate[bot]

packages/gatsby/package.json

@@ -52,7 +52,7 @@
     "del": "^3.0.0",
     "detect-port": "^1.3.0",
     "devcert-san": "^0.3.3",
-    "dotenv": "^4.0.0",
+    "dotenv": "^8.1.0",
     "eslint": "^5.16.0",
     "eslint-config-react-app": "^4.0.1",
     "eslint-loader": "^2.2.1",

yarn.lock

@@ -6741,9 +6741,10 @@ dot-prop@^4.1.0, dot-prop@^4.1.1, dot-prop@^4.2.0:
   dependencies:
     is-obj "^1.0.0"
 
-dotenv@^4.0.0:
-  version "4.0.0"
-  resolved "https://registry.yarnpkg.com/dotenv/-/dotenv-4.0.0.tgz#864ef1379aced55ce6f95debecdce179f7a0cd1d"
+dotenv@^8.1.0:
+  version "8.1.0"
+  resolved "https://registry.yarnpkg.com/dotenv/-/dotenv-8.1.0.tgz#d811e178652bfb8a1e593c6dd704ec7e90d85ea2"
+  integrity sha512-GUE3gqcDCaMltj2++g6bRQ5rBJWtkWTmqmD0fo1RnnMuUqHNCt2oTPeDnS9n6fKYvlhn7AeBkb38lymBtWBQdA==
 
 download@^6.2.2:
   version "6.2.5"