fix(deps): update dependency jwt-decode to v3 (#4408)

Co-authored-by: Renovate Bot <bot@renovateapp.com>

packages/netlify-cms-backend-git-gateway/package.json

@@ -23,7 +23,7 @@
   "dependencies": {
     "gotrue-js": "^0.9.24",
     "ini": "^1.3.5",
-    "jwt-decode": "^2.2.0",
+    "jwt-decode": "^3.0.0",
     "minimatch": "^3.0.4"
   },
   "peerDependencies": {

packages/netlify-cms-core/package.json

@@ -38,7 +38,7 @@
     "history": "^4.7.2",
     "immer": "^7.0.0",
     "js-base64": "^3.0.0",
-    "jwt-decode": "^2.1.0",
+    "jwt-decode": "^3.0.0",
     "node-polyglot": "^2.3.0",
     "prop-types": "^15.7.2",
     "react": "^16.8.4",