fix: Add timestamp to TransformableInfo interface

[jpramos123]

Simples solution to #250. Simply add the timestamp to the interface

[petarpetrov88]

Check out my PR I think it is a better solution because yours fix it only for the timestamp issue. Also my fix works for newer version of TS.

[wbt]

Is this property guaranteed to always exist, or would adding this as a required property (i.e. without ? before :) cause some code that now works (perhaps without timestamp) to stop working?

[jpramos123]

Is this property guaranteed to always exist, or would adding this as a required property (i.e. with out ? before :) cause some code that now works (perhaps without timestamp) to stop working?

By making the same change, and not using timestamp, it looks like the code won't break.

Using winston log format:

const logFormat = printf(({ level, message }) => {
    return `${level}: ${message}`;
});

[wbt]

I wasn't referring specifically to your code, but asking generally about any code.
Can you imagine any code that works now that would not work with this patch applied to logform?