Date formatting specifier availabe

[c-git]

The follow is based on the docs for jiff and chrono.

Unless I'm mistaken there are specifiers available for fractional seconds %f.

umya-spreadsheet/src/helper/number_format/date_formater.rs

Lines 51 to 52 in 9b7e2bf

	// fractional seconds - no rust equivalent
	(".s", ""),

[MathNya]

@c-git
Thank you.
I will use %f.

[c-git]

Ok I'll add it again to the same PR and again if needed we can split it.