Update connector-x to latest commit of original repo by rgieseke · Pull Request #272 · roapi/roapi

This updates connextor-x to the latest commit of the original repo to get the build working again.

sfu-db/connector-x has updated to to r2d2_mysql 23, the roapi fork was an update to version 22, so I think the fork is not needed anymore.

https://github.com/sfu-db/connector-x/blob/962b396857979c813486ad842e91a0c21ce55f72/connectorx/Cargo.toml#L46

roapi/connector-x@31d2730

Closes #271