[Firebird-website] fix on firebird roadmap for 2.0.x

[marius a. p. <ma...@gm...>]

Firebird v2.0 series has been discontinued, so no further maintenance
releases will be available. The last one released this year is
Firebird 2.0.7.

Should be (delete this year)

Firebird v2.0 series has been discontinued, so no further maintenance
releases will be available. The last one released is Firebird 2.0.7.