tests: add "use strict" and declare v5.10.1 compatibility

strict.pm helped me find a typo in an upcoming recent change, so
ensure we use it since it does more good than harm.  We'll also
take the opportunity here to declare v5.10.1 compatibility level
to future-proof against Perl incompatibilities.

1 files changed, 2 insertions, 0 deletions

diff --git a/xt/eml_check_limits.t b/xt/eml_check_limits.t
index cf780c77..9f821946 100644
--- a/xt/eml_check_limits.t
+++ b/xt/eml_check_limits.t
@@ -1,6 +1,8 @@
 #!perl -w
 # Copyright (C) 2020 all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+use strict;
+use v5.10.1;
 use Test::More;
 use PublicInbox::TestCommon;
 use PublicInbox::Eml;