Fix rate limiter window duration (#424)

Gubernator's duration parameter should be in miliseconds, according to their own documentation: https://github.com/mailgun/gubernator/blob/v1.0.1-rc.1/README.md?plain=1#L41.

ratelimit/http.go

@@ -65,7 +65,7 @@ func WithSharedRateLimiter(logger log.Logger, client SharedRateLimiter, configs
 				name:     requestName,
 				key:      fmt.Sprintf("%s:%s", c.Tenant, c.Matcher.String()),
 				limit:    int64(c.Limit),
-				duration: c.Window.Microseconds(),
+				duration: c.Window.Milliseconds(),
 			}}.Handler})
 	}