Use dbus instead of zbus for desktop notifications

[osa1]

zbus adds an entire async runtime to the binary and brings 90 dependencies (102 to 192).

The final release binary size is 8.2M (4.2M stripped) with zbus and 6.3M (2.8M stripped) with dbus. Statically linked, 8.5M (4.4M stripped) with zbus and 6.8M (3.1M stripped).

Since the dbus runtime dependency is fairly common (for example used by the google-chrome package on Ubuntu) I suspect most users will already have it installed, or at least will be able to easily install it.

Runtime dependencies before:

linux-vdso.so.1
libgcc_s.so.1
libc.so.6
/lib64/ld-linux-x86-64.so.2

After:

linux-vdso.so.1
libdbus-1.so.3
libgcc_s.so.1
libc.so.6
/lib64/ld-linux-x86-64.so.2
libsystemd.so.0
liblzma.so.5
libzstd.so.1
liblz4.so.1
libcap.so.2
libgcrypt.so.20
libgpg-error.so.0

[osa1]

@ralphptorres could you check if this builds and runs with your changes in #421? I suspect the part depends=(... dbus) should be enough but I'm not sure. I don't use Arch so I can't try myself.

[ralphptorres]

Can confirm that it builds and runs fine. Also found out that dbus and the other runtime deps above are already included in base (or its deps like systemd), which every Arch install has. So I guess we can just remove dbus as a dependency?

Also, do you prefer this feature flag over the zbus one? If so, we can update the PKGBUILD in #421.

[ralphptorres]

Decided to include dbus as dependency despite my previous argument.