Setting invalid TLS cert path does not yield error in 6.2.20

I'm maintainer of a library FDBSwift, and yesterday (after upgrading my local FoundationDB server and client) I noticed that one of my tests is failing, the one that tests that providing an invalid (non-existent) TLS cert path as `FDB_NET_OPTION_TLS_CERT_PATH` network option yields an error.

Ultimately it [expects](https://github.com/kirilltitov/FDBSwift/blob/844f1d52bdaf9df6cf0f1e1640c60d1eb9894e77/Tests/FDBTests/FDBTests.swift#L274-L277) `fdb_network_set_option` to return a non-zero `fdb_error_t` for obviously invalid options arguments (on high-level it's a Swift `Error`, of course).

However, in FoundationDB **6.2.20** it does not return an error code anymore (just zero), whereas in version **6.2.7**, which I had prior to upgrade, `fdb_network_set_option` [returns code `1513` (`File could not be read`)](https://github.com/kirilltitov/FDBSwift/pull/57/checks?check_run_id=753929237#step:3:1017).

[Same](https://github.com/kirilltitov/FDBSwift/pull/57/checks?check_run_id=753929237#step:3:1019) for `FDB_NET_OPTION_TLS_CERT_BYTES` option (expected code `2107`), didn't test other options.