feat: Update package.json to 0.1.20

Author: github-actions[bot]

src/R3.Godot/addons/R3.Godot/plugin.cfg

@@ -3,6 +3,6 @@
 name="R3.Godot"
 description="The new future of dotnet/reactive and UniRx."
 author="Cysharp"
-version="0.1.19"
+version="0.1.20"
 language="C-sharp"
 script="GodotR3Plugin.cs"

src/R3.Unity/Assets/R3.Unity/package.json

@@ -2,7 +2,7 @@
     "name": "com.cysharp.r3",
     "displayName": "R3",
     "author": { "name": "Cysharp, Inc.", "url": "https://cysharp.co.jp/en/" },
-    "version": "0.1.19",
+    "version": "0.1.20",
     "unity": "2021.3",
     "description": "Reactive Extensions for Unity.",
     "keywords": [ "rx", "event", "Scripting" ],