docs/requirements: update to urllib3>=1.23
docs/requirements: update to urllib3>=1.23
coreos/etcd,rnaveiras/etcd,mqliang/etcd,li-ang/etcd,joshix/etcd,ajityagaty/etcd,rnaveiras/etcd,cockroachdb/etcd,mkumatag/etcd,dannysauer/etcd,mkumatag/etcd,ajityagaty/etcd,cockroachdb/etcd,mqliang/etcd,etcd-io/etcd,gyuho/etcd,etcd-io/etcd,li-ang/etcd,joshix/etcd,etcd-io/etcd,dannysauer/etcd,ajityagaty/etcd,mkumatag/etcd,mqliang/etcd,gyuho/etcd,rnaveiras/etcd,coreos/etcd