configs: Add IPV6 config to sandbox_defconfig

Allow to use IPV6 tests in sandbox

Signed-off-by: Viacheslav Mitrofanov <v.v.mitrofanov@yadro.com>
diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 07fe0c3..404e4a3 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -333,3 +333,4 @@
 CONFIG_UNIT_TEST=y
 CONFIG_UT_TIME=y
 CONFIG_UT_DM=y
+CONFIG_IPV6=y