Add "sslrootcert" to knownKeys in PgsqlDriver

[jakubenglicky]

Add key sslrootcert for define path to CA Root Cert, if sslmode: verify-ca defined.

[hrach]

Couldl you please update

dbal/docs/default.md

Line 29 in cd66332

| `ssl*` | *MySQL only*; use `sslKey`, `sslCert`, `sslCa`, `sslCapath` and `sslCipher` to set SSL options for connection; |

as well? I.e. add pgsql options there :) thx

[hrach]

@jakubenglicky does it work for you? :)

[jakubenglicky]

@jakubenglicky does it work for you? :)

Unfortunately, it's not working. Please leave it open for a while. I can see the correct path to the certificate in the connection string, but I still get an exception, even though i defined path like that /etc/do-certs/ca-certificate.crt

[jakubenglicky]

@hrach Hi. Now, it's work! Is it possible to merge it?

[hrach]

@jakubenglicky thx, both keys are correct/needed? :) thx

[hrach]

Docs here https://www.postgresql.org/docs/current/libpq-connect.html
Maybe we miss sslkey as well :)