Await turbo stream insertion in DOM (#36)

* Merge upstream

* Wait for turbo streams to be added to DOM

Author: excid3

src/fetch_request.js

@@ -26,7 +26,7 @@ export class FetchRequest {
     }
 
     if (response.ok && response.isTurboStream) {
-      response.renderTurboStream()
+      await response.renderTurboStream()
     }
 
     return response

src/fetch_response.js

@@ -64,7 +64,7 @@ export class FetchResponse {
   async renderTurboStream () {
     if (this.isTurboStream) {
       if (window.Turbo) {
-        window.Turbo.renderStreamMessage(await this.text)
+        await window.Turbo.renderStreamMessage(await this.text)
       } else {
         console.warn('You must set `window.Turbo = Turbo` to automatically process Turbo Stream events with request.js')
       }