Fix issues where the driver didn't load the postgres adapter

[CloCkWeRX]

If you are running with sqlite only and pass in the right env variables you can end up with:

StandardError: An error has occurred, this and all later migrations canceled: (StandardError)

uninitialized constant PG
/opt/hostedtoolcache/Ruby/3.4.5/x64/bin/bundle:25:in 'Kernel#load'
/opt/hostedtoolcache/Ruby/3.4.5/x64/bin/bundle:25:in '<main>'

Caused by:
NameError: uninitialized constant PG (NameError)

      if conn.is_a?(::PG::Connection)
                    ^^^^
/opt/hostedtoolcache/Ruby/3.4.5/x64/bin/bundle:25:in 'Kernel#load'
/opt/hostedtoolcache/Ruby/3.4.5/x64/bin/bundle:25:in '<main>'

[CloCkWeRX]

#1017