chore: bump ts peer dep to 3.4

Author: simonhaenisch

package.json

@@ -28,7 +28,7 @@
     "typescript": "4.2.4"
   },
   "peerDependencies": {
-    "typescript": ">=3.x"
+    "typescript": ">=3.4"
   },
   "prettier": {
     "printWidth": 120,