fix: aur build failed: sd-bus-provider set to auto

[BenSYZ]

swayfx/meson.build:92:2: ERROR: Assert failed: sd-bus-provider must
not be set to auto since auto_features != auto

[BenSYZ]

Hey guys! Today I failed to build swayfx on my arch, even with makechrootpkg. So I try to make a simple search and find this. From the error message and this commit, it seems that the problem comes from not specifying of sd-bus-provider manually. And I find this man page. It seems that arch use libsystemd as sd-bus-provider. I'm not fully sure about this. But when I add the -Dsd-bus-provider=libsystemd. The compilation is passed. Hope this pr is proper and helpful.

[WillPower3309]

Thanks!

[BenSYZ]

No problem.