Add pg-builder to the list

[sad-spirit]

pg-builder allows one to build SQL (Postgres dialect specifically) working directly with query AST. The latter can be created either from scratch or from existing SQL, as the package contains a reimplementation of Postgres query parser.

[sad-spirit]

As this list does seem to be updated, I'd like to remind of my pull request. If you have any questions about the proposed package I'll gladly answer them.