Update README.md

Update install url to reflect newest version. I tried sse and hunted multiple hours for bugs with my sse-close implementation, which just didn't exist yet in the 2.0.0 version.

src/sse/README.md

@@ -14,7 +14,7 @@ Use the following attributes to configure how SSE connections behave:
 ## Install
 
 ```html
-<script src="https://unpkg.com/htmx-ext-sse@2.0.0/sse.js"></script>
+<script src="https://unpkg.com/htmx-ext-sse@2.2.0/sse.js"></script>
 ```
 
 ## Usage