m4: Fix check for Python 3.6 version. #3266

Job	Run time
dpdk gcc (ubuntu-24.04)	9s
libreswan (ubuntu-24.04)	5s
linux deb no dpdk	5m 28s
linux rpm fedora	4m 14s
osx clang --disable-ssl	1m 52s
clang-analyze-cache	10m 44s
linux gcc --disable-ssl	2m 51s
linux clang --disable-ssl	2m 50s
linux gcc c99	2m 40s
linux clang c99	2m 46s
linux gcc test	9m 15s
linux clang address,undefined test	21m 11s
linux gcc test --enable-shared	11m 49s
linux clang test --enable-shared	11m 28s
linux gcc check check-dpdk dpdk	18m 51s
linux clang check check-dpdk dpdk	18m 25s
linux gcc test -ljemalloc	8m 59s
linux clang test -ljemalloc	8m 54s
linux gcc --enable-afxdp	2m 54s
linux clang --enable-afxdp	2m 31s
linux gcc dpdk --enable-shared	3m 53s
linux clang dpdk --enable-shared	3m 54s
linux gcc dpdk-shared	2m 57s
linux clang dpdk-shared	3m 6s
linux gcc dpdk-shared --enable-shared	4m 1s
linux clang dpdk-shared --enable-shared	3m 42s
linux gcc m32 --disable-ssl	2m 53s
linux gcc check-ovsdb-cluster	7m 11s
linux gcc check-kernel -100	10m 59s
linux gcc check-kernel 100-	16m 54s
linux clang address,undefined check-kernel -100	13m 23s
linux clang address,undefined check-kernel 100-	18m 32s
linux gcc check-offloads -100	11m 37s
linux gcc check-offloads 100-	11m 33s
linux gcc dpdk check-system-userspace	12m 30s
linux clang address,undefined dpdk check-system-userspace	15m 51s
linux gcc dpdk check-system-tso	12m 14s
linux gcc dpdk check-afxdp	11m 55s
clang-analyze	10m 26s
	5h 25m 27s

Provide feedback