Support tlsversion connection string option

[bgrainger]

Connector/NET 8.0.19 adds tlsversion. It's a comma-delimited list of TLS protocol versions to support, defaulting to Tlsv1,Tlsv1.1,Tlsv1.2,Tlsv1.3.

[bgrainger]

This could be useful to ensure that older (and insecure) TLS versions aren't used (when system TLS versions can't be controlled by the user).

[bgrainger]

Added in 0.64.0.