Fix warning sign compare (#80) #187

Job	Run time
Code formatting	20s
Check Ruby Samples ubuntu-latest	2m 23s
Check Ruby Samples macos-latest	2m 25s
Exercise Python examples on ubuntu-latest	4m 51s
Exercise Python examples on macos-latest	8m 52s
Build Windows fetch	4m 36s
Build Windows vcpkg	10m 27s
Build ubuntu-20.04 gcc os	1m 15s
Build ubuntu-20.04 gcc fetch	1m 52s
Build ubuntu-20.04 gcc vcpkg	4m 21s
Build ubuntu-20.04 clang os	1m 17s
Build ubuntu-20.04 clang fetch	3m 20s
Build ubuntu-20.04 clang vcpkg	6m 5s
Build macos-latest gcc os	2m 20s
Build macos-latest gcc fetch	3m 1s
Build macos-latest gcc vcpkg	2m 55s
Build macos-latest clang os	4m 49s
Build macos-latest clang fetch	5m 3s
Build macos-latest clang vcpkg	2m 25s
	1h 12m 37s

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