chore: change github mirror #700

Job	Run time
build-macos (x86_64, x64-osx, mono, macos.amd64)	3m 41s
build-windows (Win32, x86-windows-static, windows.i386)	27m 59s
build-linux (g++-8, gcc-8, g++-8, x64-linux, mono, linux.amd64)	4m 3s
build-macos (arm64, arm64-osx, mono, macos.aarch64)	6m 55s
build-windows (x64, x64-windows-static, windows.amd64)	27m 44s
build-linux (/usr/i686-linux-gnu, g++-8-i686-linux-gnu, i686-linux-gnu-gcc-8, i686-linux-gnu-g++-...	2m 26s
build-linux (/usr/aarch64-linux-gnu, g++-aarch64-linux-gnu, aarch64-linux-gnu-gcc, aarch64-linux-...	3m 46s
build-linux (/usr/arm-linux-gnueabihf, g++-arm-linux-gnueabihf, arm-linux-gnueabihf-gcc, arm-linu...	3m 30s
	1h 20m 4s

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