Remove unused module import

The dbi sqlite module is not directly used in the site-generator code.
The module is called by template files. Removing it allows the main
code to be database independent.

site-generator

@@ -122,7 +122,6 @@ use Text::CSV_XS;
 use HTML::Entities qw(encode_entities);
 use Date::Calc;
 use DBI;
-use DBD::SQLite;
 use Tie::DBI;
 use Template;
 use Template::Plugin::Date;