GHA: Suppress warnings #695

Job	Run time
build-cross (x86_64-w64-mingw32)	1m 21s
build-cross (i686-w64-mingw32)	1m 10s
build-windows (x86)	1m 19s
build-windows (x64)	1m 30s
build (ubuntu-22.04, gcc, autotools)	1m 12s
build (ubuntu-22.04, gcc, cmake)	1m 11s
build (ubuntu-22.04, clang, autotools)	1m 11s
build (ubuntu-22.04, clang, distcheck)	53s
build (ubuntu-22.04, clang, cmake)	42s
build (macos-13, gcc, autotools)	1m 24s
build (macos-13, gcc, cmake)	1m 16s
build (macos-13, clang, autotools)	1m 4s
build (macos-13, clang, distcheck)	1m 26s
build (macos-13, clang, cmake)	1m 19s
build (macos-14, gcc, autotools)	40s
build (macos-14, gcc, cmake)	41s
build (macos-14, clang, autotools)	48s
build (macos-14, clang, distcheck)	53s
build (macos-14, clang, cmake)	38s
release	0s
	20m 38s

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