Also build with "all" feature combinations

[squell]

ntpd-rs doesn't build with --no-default-features.

E.g. for the ntpd/ subcrate, the pps feature is required to prevent a compile error; for other parts std and serde are necessary.

I'd suggest adding some cargo check steps for all feature combinations in CI.

[squell]

Note: if we support swapping between openssl and aws-lc, of course one of those features needs to be enabled for tests to succeed (although a simple `cargo check --tests would still work)

[davidv1992]

Done