Missing types convertion for PostgreSQL

[marimeireles]

Not all PostgreSQL types are covered by the switch:

Here's the warning:

2020-12-31T12:15:04.9844840Z /Users/runner/work/1/s/include/xeus-sql/soci_handler.hpp:31:27: warning: comparison of integers of different signs: 'int' and 'std::__1::vector<std::__1::basic_string<char>, std::__1::allocator<std::__1::basic_string<char> > >::size_type' (aka 'unsigned long') [-Wsign-compare]
2020-12-31T12:15:04.9846930Z         for (int i = 2; i < tokenized_input.size(); i++)
2020-12-31T12:15:04.9847270Z                         ~ ^ ~~~~~~~~~~~~~~~~~~~~~~
2020-12-31T12:15:05.0122330Z /Users/runner/work/1/s/src/xeus_sql_interpreter.cpp:70:24: warning: enumeration values 'dt_blob' and 'dt_xml' not handled in switch [-Wswitch]
2020-12-31T12:15:05.0123010Z                 switch(props.get_data_type())
2020-12-31T12:15:05.0123320Z                        ^
2020-12-31T12:15:05.0188040Z /Users/runner/work/1/s/src/xeus_sql_interpreter.cpp:70:24: note: add missing switch cases
2020-12-31T12:15:05.0188630Z                 switch(props.get_data_type())
2020-12-31T12:15:05.0188930Z                        ^
2020-12-31T12:17:02.8016670Z 2 warnings generated.