[test] exclude PG test
[test] exclude PG test

The test does a query with multiple COALESCE() expressions w/o an
alias and PG returns the same column label for all of them. This messes
up type mapping and might not be fixable easily.

jruby/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,jruby/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter,bruceadams/activerecord-jdbc-adapter