third_party:quic Fix compilation with clang-20

third_party:quic Fix compilation with clang-20

Add -Wno-error=format-nonliteral so that quic builds with clang 20

../../third_party/quic/libquic/handshake.c:106:35: error:
   format string is not a string literal [-Werror,-Wformat-nonliteral]
  106 |         rc = vsnprintf(msg, sizeof(msg), fmt, arg);
      |                                          ^~~
../../third_party/quic/libquic/handshake.c:135:35: error:
   format string is not a string literal [-Werror,-Wformat-nonliteral]
  135 |         rc = vsnprintf(msg, sizeof(msg), fmt, arg);
      |                                          ^~~
../../third_party/quic/libquic/handshake.c:164:35: error:
   format string is not a string literal [-Werror,-Wformat-nonliteral]
  164 |         rc = vsnprintf(msg, sizeof(msg), fmt, arg);
      |                                          ^~~

Signed-off-by: Gary Lockyer <gary@catalyst.net.nz>
Reviewed-by: Stefan Metzmacher <metze@samba.org>