Add min date for milestone

[Giuliano1993]

Fixes Issue

Closes #8926

Changes proposed

• added a front-end control in input field as min date
• added a backend control in milestone schema with min date

Check List (Check all the applicable boxes)

• My code follows the code style of this project.
• My change requires changes to the documentation.
• [] I have updated the documentation accordingly.
• All new and existing tests passed.
• This PR does not contain plagiarized content.
• The title of my pull request is a short description of the requested changes.

Screenshots

Note to reviewers

I added as min date 01-01-1950 as it seemed a reasonable limit to me, but can be changed if is not good enough

[accodes21]

Looks good to me.

[eddiejaoude]

Thank you for the contribution 👍

Why 1950 as the min date? Maybe 1970 is better?

[Giuliano1993]

Yeah @eddiejaoude probably 1970 will be better; 1950 was actually still way too back! Gonna change it in a moment!

[eddiejaoude]

Great! Thank you 👍