Also zero the public key and nonce after encryption in crypto_box_seal()

src/libsodium/crypto_box/crypto_box_seal.c

@@ -35,6 +35,8 @@ crypto_box_seal(unsigned char *c, const unsigned char *m,
     _crypto_box_seal_nonce(nonce, epk, pk);
     ret = crypto_box_easy(c + crypto_box_PUBLICKEYBYTES, m, mlen,
                           nonce, pk, esk);
+    sodium_memzero(nonce, sizeof nonce);
+    sodium_memzero(epk, sizeof epk);
     sodium_memzero(esk, sizeof esk);
 
     return ret;