[dnssec] sign tests: fix sample DSA signature

One octet 'T' field was missing.

dnssec/tests/sign.c

@@ -24,7 +24,8 @@ static const dnssec_binary_t signed_rsa = { .size = 64, .data = (uint8_t []) {
 	0xc0, 0x03, 0x5a, 0xab,
 }};
 
-static const dnssec_binary_t signed_dsa = { .size = 40, .data = (uint8_t []) {
+static const dnssec_binary_t signed_dsa = { .size = 41, .data = (uint8_t []) {
+	0x03,
 	0x8c, 0xd9, 0x4b, 0xcc, 0xdb, 0xf4, 0x3f, 0x91, 0x0e, 0x7e,
 	0x76, 0x1d, 0x87, 0xda, 0x48, 0xdd, 0x65, 0x7a, 0x57, 0x25,
 	0x97, 0x0a, 0x13, 0xa5, 0x4a, 0xb3, 0xff, 0x62, 0xfd, 0x2c,