Changes for running in Phoenix 1.7

[donapieppo]

I was having problems to run this on Proenix 1.7 and tried to update.
While solving issues with the update i got inspired and made a lot of changes on my fork in order
to:

• use ~p sigil instead if Routes.static_path
• use streams (phx-update="append" is deprecated)
• use of .simple_form and .table from CoreComponents
• use of Tailwind css
• use Calendar instead of NimbleStrftime

I also choose to simplify the installation using sqlite3.

You can find the fork at donapieppo/phoenix_live_view_example . I am no real expert in elixir/phoenix so before proposing a coherent pull I'd like a small review from who is :-)