net/rustconn: Update to 0.10.12

ChangeLog:

• https://github.com/totoshko88/RustConn/releases/tag/v0.10.10
• https://github.com/totoshko88/RustConn/releases/tag/v0.10.11
• https://github.com/totoshko88/RustConn/releases/tag/v0.10.12

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