systemd-services/tailscale: use nftables backend

The iptables frontend for nftables seems to not play nice. Since we use nftables in postmarketOS anyway, tell tailscale to use it directly. This fixes routing not working and the following error seen in tailscale status

- adding [-i tailscale0 -j MARK --set-mark 0x40000/0xff0000] in v4/filter/ts-forward: running [/usr/sbin/iptables -t filter -A ts-forward -i tailscale0 -j MARK --set-mark 0x40000/0xff0000 --wait]: exit status 2: Warning: Extension MARK revision 0 not supported, missing kernel module?

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mentioned in commit f2e83e42

added 31 commits

• d290979d...2d103255 - 30 commits from branch master
• f2e83e42 - systemd-services/tailscale: use nftables backend

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approved this merge request

LGTM, thanks!

enabled an automatic merge when all merge checks for f2e83e42 pass

merged