Fix warning sign compare #177

Job	Run time
Code formatting	14s
Check Ruby Samples ubuntu-latest	2m 15s
Check Ruby Samples macos-latest	4m 16s
Exercise Python examples on ubuntu-latest	5m 15s
Exercise Python examples on macos-latest	8m 57s
Build Windows fetch	4m 20s
Build Windows vcpkg	12m 40s
Build ubuntu-20.04 gcc os	1s
Build ubuntu-20.04 gcc fetch	1s
Build ubuntu-20.04 gcc vcpkg	1s
Build ubuntu-20.04 clang os	1m 6s
Build ubuntu-20.04 clang fetch	2m 38s
Build ubuntu-20.04 clang vcpkg	5m 30s
Build macos-latest gcc os	3m 13s
Build macos-latest gcc fetch	3m 51s
Build macos-latest gcc vcpkg	5m 25s
Build macos-latest clang os	3m 10s
Build macos-latest clang fetch	3m 12s
Build macos-latest clang vcpkg	3m 35s
	1h 9m 40s

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