[functional test] v3 transaction submission

Co-authored-by: Suhas Daftuar <sdaftuar@gmail.com>
Co-authored-by: Gregory Sanders <gsanders87@gmail.com>

test/functional/test_runner.py

@@ -260,6 +260,7 @@ BASE_SCRIPTS = [
     'p2p_invalid_tx.py --v2transport',
     'p2p_v2_transport.py',
     'example_test.py',
+    'mempool_accept_v3.py',
     'wallet_txn_doublespend.py --legacy-wallet',
     'wallet_multisig_descriptor_psbt.py --descriptors',
     'wallet_txn_doublespend.py --descriptors',