net/rustconn: Update to 0.19.16

ChangeLog:

• https://github.com/totoshko88/RustConn/releases/tag/v0.19.12
• https://github.com/totoshko88/RustConn/releases/tag/v0.19.13
• https://github.com/totoshko88/RustConn/releases/tag/v0.19.14
• https://github.com/totoshko88/RustConn/releases/tag/v0.19.15
• https://github.com/totoshko88/RustConn/releases/tag/v0.19.16

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