Upgrade nftnl to 0.3 and all dependencies needed to make it build

[faern]

We recently released nftnl 0.3 that deals with a number of things. It adds support for a lot of stuff we need for Linux split tunneling, but it also fixes compilation errors on ARM.

... And it upgrades the broken err-derive dependency to the newer 0.2 series. This however also caused a lot of headache as that series is also broken on a bit older combination of dependencies. I had to do cargo update -p $dep for every dep of err-derive in order to make it build again. It needed the very latest syn, quote etc to work.

Git checklist:

• Describe the change in CHANGELOG.md under the [Unreleased] header.
• Check that commits follow the Mullvad coding guidelines

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This change is 

[dlon]

Reviewed 2 of 2 files at r1.
Reviewable status: complete! all files reviewed, all discussions resolved