[PATCH] t/nntpd.t: avoid `used only once' warning

[Eric Wong]

We can't use cross-package `our' variables without `use'-ing the
package, first.
---
 t/nntpd.t | 1 +
 1 file changed, 1 insertion(+)

diff --git a/t/nntpd.t b/t/nntpd.t
index ab6876bb..80df4dc5 100644
--- a/t/nntpd.t
+++ b/t/nntpd.t
@@ -8,6 +8,7 @@ use Socket qw(IPPROTO_TCP TCP_NODELAY);
 use Sys::Hostname;
 use POSIX qw(_exit);
 use PublicInbox::SHA;
+use PublicInbox::DS;
 
 # t/nntpd-v2.t wraps this for v2
 my $version = $ENV{PI_TEST_VERSION} || 1;