[Clean Code] Magic numbers

[GabrielDVpereira]

In some files, I found some numbers in the code that means something in the code, but for new collaborators it may confuse to understand what is happening. I found some of them in the following files:

• src/ARte/users/jinja2/users/artwork-create.jinja2
• src/ARte/users/jinja2/users/artwork-edit.jinja2
• src/ARte/users/jinja2/users/exhibit-create.jinja2
• src/ARte/users/jinja2/users/exhibit-edit.jinja2