cmake: Suppress invalid escape sequence warnings with Python 3.12 #909

Job	Run time
Build on ubuntu-20.04 g++-7	45s
Build on ubuntu20.04 aarch64 g++-8	7m 0s
Build on ubuntu20.04 aarch64 g++-9	7m 23s
Build on ubuntu20.04 aarch64 g++-10	8m 24s
Build on ubuntu22.04 aarch64 g++-12	7m 34s
Build on ubuntu-20.04 g++-8	51s
Build on ubuntu20.04 aarch64 clang-9	11m 31s
Build on ubuntu-latest g++-9	1m 16s
Build on ubuntu20.04 aarch64 clang-10	10m 41s
Build on ubuntu-latest g++-10	1m 16s
Build on ubuntu22.04 aarch64 clang-14	10m 54s
Build on ubuntu-20.04 clang-7	53s
Build on ubuntu22.04 armv7 g++	6m 46s
Build on ubuntu-20.04 clang-8	58s
Build on ubuntu22.04 ppc64le g++-12	6m 17s
Build on ubuntu-20.04 clang-9	1m 0s
Build on ubuntu22.04 s390x g++-12	6m 4s
Build on ubuntu-20.04 clang-10	1m 13s
Build on ubuntu22.04 riscv64 g++-12	6m 16s
Build on ubuntu-20.04 clang-11	1m 0s
Build on ubuntu-latest clang-12	1m 9s
Build on ubuntu-latest clang-13	52s
Build on ubuntu-latest clang-14	53s
build-macos (macos-latest)	29s
build-macos (flyci-macos-large-latest-m2)	22s
Build static on ubuntu-latest	1m 51s
build-windows	2m 8s
	1h 45m 46s

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