Update to TypeScript v4.0

package.json

@@ -93,7 +93,7 @@
     "terser": "^5.0.0",
     "through2": "^4.0.1",
     "tiny-emitter": "^2.0.2",
-    "typescript": "^3.9.5",
+    "typescript": "^4.0.2",
     "unorm": "^1.3.3",
     "vinyl": "^2.2.0",
     "watchify": "^3.7.0",

yarn.lock

@@ -7795,10 +7795,10 @@ typedarray@^0.0.6:
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
   integrity sha1-hnrHTjhkGHsdPUfZlqeOxciDB3c=
 
-typescript@^3.9.5:
-  version "3.9.7"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-3.9.7.tgz#98d600a5ebdc38f40cb277522f12dc800e9e25fa"
-  integrity sha512-BLbiRkiBzAwsjut4x/dsibSTB6yWpwT5qWmC2OfuCg3GgVQCSgMs4vEctYPhsaGtd0AeuuHMkjZ2h2WG8MSzRw==
+typescript@^4.0.2:
+  version "4.0.2"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-4.0.2.tgz#7ea7c88777c723c681e33bf7988be5d008d05ac2"
+  integrity sha512-e4ERvRV2wb+rRZ/IQeb3jm2VxBsirQLpQhdxplZ2MEzGvDkkMmPglecnNDfSUBivMjP93vRbngYYDQqQ/78bcQ==
 
 ua-parser-js@0.7.21:
   version "0.7.21"