Address sscanf vulnerability #1781

Job	Run time
freebsd13 (CMake) (LLVM)	7m 29s
freebsd14 (CMake) (LLVM)	7m 2s
debian:11 (CMake) (GNU)	2m 58s
debian:12 (Latest Mapnik) (CMake) (GNU)	3m 19s
debian:12 (CMake) (GNU)	3m 5s
ubuntu:22.04 (Latest Mapnik) (CMake) (GNU)	3m 22s
debian:testing (CMake) (GNU)	3m 3s
macos-12 (CMake) (LLVM)	10m 35s
macos-13 (Autotools) (LLVM)	12m 17s
fedora:38 (CMake) (GNU)	3m 30s
fedora:39 (CMake) (GNU)	4m 6s
macos-13 (CMake) (LLVM)	15m 45s
fedora:rawhide (CMake) (GNU)	3m 2s
opensuse/leap:15 (CMake) (GNU)	6m 8s
quay.io/centos/centos:stream8 (CMake) (GNU)	11m 40s
quay.io/centos/centos:stream9 (CMake) (GNU)	5m 32s
ubuntu:20.04 (CMake) (GNU)	3m 14s
ubuntu:rolling (CMake) (GNU)	2m 38s
ubuntu:22.04 (Autotools) (GNU)	1m 49s
ubuntu:22.04 (Autotools) (LLVM)	1m 52s
ubuntu:22.04 (CMake) (GNU)	2m 47s
ubuntu:22.04 (CMake) (LLVM)	2m 42s
	1h 57m 55s

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