tls: stop sending ssl_renegotiation_limit in startup message

[tejasmanohar]

This addresses #321 with the
fix @jackc proposed there--

The only reason we send ssl_renegotiation_limit is to avoid mysterious connection errors when connecting to servers that use renegotiation. But PostgreSQL defaults to 0 for all supported versions, and removed the setting for 9.6. So I guess all we need to do is remove the default startup parameter message. Anyone who really needs it can easily add it back with ConnConfig.RuntimeParams.

Redshift users that need to connect
w/ SSL currently fork the library to delete this parameter, e.g.

segmentio@8e0028d

And, that's annoying to keep up-to-date :)

[tejasmanohar]

As expressed in doc.go, I think this fix should go in v3.3.0. While I doubt this breaks connections for many, I suppose it could if a user of this library ignores warnings and has a non-zero value for this parameter set in postgresql.conf in Postgres < 9.6. That said, I don't feel strongly :P

[jackc]

Thanks. I agree it is reasonable to make this change in a minor release. It's really hard to imagine a case where it would cause breakage.

[tejasmanohar]

@jackc Thanks for merging this. Would you please publish a v3.3.0 tag? Or, are you waiting on something else to do that? The docs change merged in this PR mentions this being available as of v3.30, and I'd like to pin vendor of my project that requires this fix to a release of pgx.

[jackc]

Okay, I released v3.3.0.

[tejasmanohar]

Appreciate it