Ensure we check/test/doc the lightning crate under dnssec

.. as we'd otherwise never catch any bugs particular to the `dnssec`
feature.

Author: tnull

ci/ci-tests.sh

@@ -74,6 +74,11 @@ for DIR in "${WORKSPACE_MEMBERS[@]}"; do
 	cargo doc -p "$DIR" --document-private-items
 done
 
+echo -e "\n\nChecking and testing lightning with features"
+cargo test -p lightning --verbose --color always --features dnssec
+cargo check -p lightning --verbose --color always --features dnssec
+cargo doc -p lightning --document-private-items --features dnssec
+
 echo -e "\n\nChecking and testing Block Sync Clients with features"
 
 cargo test -p lightning-block-sync --verbose --color always --features rest-client