Aliases (`@hourly`, `@weekly`, etc.) don't work with `with_seconds_required` option

[azasypkin]

Summary

It looks like it's not possible to use the same Cron config to accept both aliases like @hourly or @weekly and standard cron expressions while requiring a seconds specifier.

let get_cron = |pattern: &str| {
    Cron::new(pattern)
        .with_seconds_required()
        .with_dom_and_dow()
        .parse()
};

get_cron("0 0 * * * *")?; -> works as expected

get_cron("@hourly")?; -> fails with `Pattern must consist of six fields, seconds can not be omitted.`

I assume it's because of this mapping:

croner-rust/src/pattern.rs

Lines 175 to 182 in 830fc53

	match pattern {
	p if eq_ignore_case(p, "@yearly") || eq_ignore_case(p, "@annually") => "0 0 1 1 *",
	p if eq_ignore_case(p, "@monthly") => "0 0 1 * *",
	p if eq_ignore_case(p, "@weekly") => "0 0 * * 0",
	p if eq_ignore_case(p, "@daily") => "0 0 * * *",
	p if eq_ignore_case(p, "@hourly") => "0 * * * *",
	_ => pattern,
	}

.

To support both, consumers of croner essentially have to re-implement the handle_nicknames logic to detect aliases and omit with_seconds_required, or even manually convert to standard syntax if the expression is just passed along to be parsed elsewhere (e.g., when croner is a transitive dependency). I ran into this issue with https://github.com/mvniekerk/tokio-cron-scheduler, which recently switched to croner from cron.

Thanks for the great library!

[Hexagon]

Thanks, great bug report!

Are you interested in making a pull request or should i have a look at it?

[Hexagon]

Hopefully fixed in 2.0.6

[azasypkin]

Wow, that was fast, thanks a lot @Hexagon!