Update Bootstrap Italia version to 2.17.1

[albx]

The Bootstrap Italia version must be updated to the current version 2.17.1 (see https://italia.github.io/bootstrap-italia/docs/come-iniziare/introduzione/#manuale)

• Update CSS
• Update SVGs
• Update fonts

[albx]

2.17.2 came out few days ago https://github.com/italia/bootstrap-italia/releases/tag/v2.17.2
So I'll update to this last version