Patterns of DateTime.fromString and DateTime.format are not aligned

[solomax]

Prerequisites

• I have searched for duplicate or closed issues.
• I have validated my setup against the latest version on StackBlitz.
• I have read the contributing guidelines.

Describe the issue

DateTime.fromString can handle single y in the pattern https://github.com/Eonasdan/tempus-dominus/blob/master/src/js/datetime.ts#L767

While DateTime.format can't: https://github.com/Eonasdan/tempus-dominus/blob/master/src/js/datetime.ts#L921

So in case localization.format with single y is used (for ex. dd.MM.y, HH:mm:ss)
The date can be parsed correctly BUT being set into input as 27.09.undefined, 14:47:41 on select

StackBlitz fork

https://codepen.io/solomax/pen/bGOeYKg

What operating system(s) are you seeing the problem on?

Linux

What browser(s) are you seeing the problem on?

Chrome, Firefox

What version of are you using? You can find this information from the sample StackBlitz.

6.7.11, 6.7.13

What your browser's locale? You can find this information from the sample StackBlitz.

en-US

[stackblitz]

Start a new pull request in StackBlitz Codeflow.

• tempus-dominus-v6-simple-setup (Open reproduction)

[solomax]

I believe the fix is trivial :)

single y should be handled exactly as yyyy :)))

[Eonasdan]

New release should fix this.