configs: Add IPV6 config to sandbox64_defconfig

Allow to use IPV6 tests in sandbox

Signed-off-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
diff --git a/configs/sandbox64_defconfig b/configs/sandbox64_defconfig
index cff166b..b69e053 100644
--- a/configs/sandbox64_defconfig
+++ b/configs/sandbox64_defconfig
@@ -258,3 +258,4 @@
 CONFIG_UNIT_TEST=y
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
+CONFIG_IPV6=y