vlan: Remove -Wconversion override

vlan: Remove -Wconversion override

Only Debian 11 (GCC 10) complains about this.
We decided not to add work-arounds for GCC 10
and older and instead accept that they do not
build -Werror clean.

Change-Id: I73c46ac630834a8cf8894aaa2dcc429fbedd3db7
Signed-off-by: Frank Lichtenheld <frank@lichtenheld.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Gerrit URL: https://gerrit.openvpn.net/c/openvpn/+/1179
Message-Id: <20251008105507.9997-1-gert@greenie.muc.de>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg33285.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>