Fix ignoring return value error.

[ghost]

Hello.
This commit removes a compile error.

I got the below error.

redisclient/src/redisclient/impl/redisasyncclient.cpp:34:9: error: ignoring return value of function declared with 'nodiscard' attribute [-Werror,-Wunused-result]
        std::move(pimpl->socket);

Algthough the below move function returns a value, ignoring it.

redisclient/src/redisclient/impl/redisasyncclient.cpp

Line 34 in fbf052e

std::move(pimpl->socket);

This error occurred in the following versions.

• clang version 11.1.0
• gcc-libs-11.1.0-1
• glibc-2.33-5