chore: switched from lib/pq to jackc/pgx/v5/stdlib

The serialization of the various datatypes to BYTEA lead to
compatability problems and pgx has shown to be creating much
less problems (demostrated on timestamps, floats, etc.)

fix: handle type mismatches in semantic diff value comparison

Two problems resolved
- int64 vs float64 comparison
- timestamp comparison

chore: updated LICENSE

chore: refactoring