chore(templates/README): update handler names re: spinframework#145

Signed-off-by: Vaughn Dice <vdice@akamai.com>

Author: vdice

README.md

@@ -57,7 +57,7 @@ cat >app.py <<EOF
 from spin_sdk import http
 from spin_sdk.http import Request, Response
 
-class WasiHttpHandler030Rc20260315(http.Handler):
+class HttpHandler(http.Handler):
     async def handle_request(self, request: Request) -> Response:
         return Response(
             200,

templates/http-py/content/app.py

@@ -1,6 +1,6 @@
 from spin_sdk.http import Handler, Request, Response
 
-class WasiHttpHandler030Rc20260315(Handler):
+class HttpHandler(Handler):
     async def handle_request(self, request: Request) -> Response:
         return Response(
             200,