PKP lib: Upgrade FontAwesome

Describe the problem you would like to solve
Integration of Mastodon icon.

Describe the solution you’d like
The icon should be available by using FontAwesome.

Who is asking for this feature?
Journal Editors.

Additional information
The FontAwesome version which is delivered with PKP lib is 4.7. The newest version of FontAwesome 6.3 includes the Mastodon icon (and many other new icons).