Issue in time unit casting

[LouisaSearch]

In source medida/src/meter.cc:

There is a casting error here: static const auto kTickInterval = Clock::duration(std::chrono::seconds(5)).count();

It will cause a long delay when the system is idle for a while

should be: static const auto kTickInterval = std::chrono::duration_caststd::chrono::nanoseconds(Clock::duration(std::chrono::seconds(5))).count();