MINOR: quic: Add the QUIC v1 initial salt.

See initial_salt value for QUIC-TLS RFC 9001 at
https://www.rfc-editor.org/rfc/rfc9001.html#name-initial-secrets
diff --git a/src/quic_tls.c b/src/quic_tls.c
index f80565e..c27946a 100644
--- a/src/quic_tls.c
+++ b/src/quic_tls.c
@@ -27,6 +27,12 @@
 	0x43, 0x90, 0xa8, 0x99
 };
 
+unsigned char initial_salt_v1[20] = {
+	0x38, 0x76, 0x2c, 0xf7, 0xf5, 0x59, 0x34, 0xb3,
+	0x4d, 0x17, 0x9a, 0xe6, 0xa4, 0xc8, 0x0c, 0xad,
+	0xcc, 0xbb, 0x7f, 0x0a
+};
+
 /* Dump the RX/TX secrets of <secs> QUIC TLS secrets. */
 void quic_tls_keys_hexdump(struct buffer *buf, struct quic_tls_secrets *secs)
 {