Update go.work.example to use go 1.21 (#5604)

DimitrisJim · web-flow · commit eeaee4b2f777 · 2024-01-15T14:07:48.000+02:00
as defined in go.mod's. breaks otherwise.
diff --git a/go.work.example b/go.work.example
@@ -1,4 +1,4 @@
-go 1.20
+go 1.21
 
 use (
 	./
