chore: initialize standalone UPM package

Tests/ShrinkNetwork.Integration.EventBus.Tests.asmdef

@@ -0,0 +1,18 @@
+{
+  "name": "ShrinkNetwork.Integration.EventBus.Tests",
+  "rootNamespace": "ShrinkNetwork.Integration.EventBus.Tests",
+  "references": [
+    "ShrinkNetwork.Integration.EventBus",
+    "ShrinkNetwork.Runtime",
+    "ShrinkEventBus.Runtime",
+    "UniTask",
+    "UnityEngine.TestRunner",
+    "UnityEditor.TestRunner"
+  ],
+  "includePlatforms": ["Editor"],
+  "excludePlatforms": [],
+  "allowUnsafeCode": false,
+  "overrideReferences": false,
+  "autoReferenced": false,
+  "defineConstraints": ["UNITY_INCLUDE_TESTS"]
+}