openssl-cmp.pod.in: fix grammar glitch #948

Job	Run time
compiler (gcc-7, ubuntu-20.04)	6m 22s
compiler (gcc-8, ubuntu-20.04)	7m 59s
compiler (gcc-9, ubuntu-20.04)	8m 4s
compiler (gcc-10, ubuntu-20.04)	7m 22s
compiler (gcc-11, ubuntu-22.04)	6m 16s
compiler (gcc-12, ubuntu-22.04)	7m 7s
compiler (gcc-13, ubuntu-22.04, ubuntu-toolchain-r/test)	8m 57s
compiler (clang-6.0, ubuntu-20.04)	1m 57s
compiler (clang-7, ubuntu-20.04)	2m 37s
compiler (clang-8, ubuntu-20.04)	2m 13s
compiler (clang-9, ubuntu-20.04)	7m 54s
compiler (clang-10, ubuntu-20.04)	8m 51s
compiler (clang-11, ubuntu-20.04)	8m 8s
compiler (clang-12, ubuntu-20.04)	6m 23s
compiler (clang-13, ubuntu-22.04)	6m 41s
compiler (clang-14, ubuntu-22.04)	6m 29s
compiler (clang-15, ubuntu-22.04, jammy)	8m 21s
compiler (clang-16, ubuntu-22.04, jammy)	6m 43s
	1h 58m 24s

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