ci: ubuntu-latest with series and version latest added. #25

Job	Run time
7.0/ubuntu-20.04/gcc/default/	1m 52s
7.0/ubuntu-20.04/gcc/static/	1m 42s
3.15/ubuntu-20.04/gcc/default/	1m 42s
3.14/ubuntu-20.04/gcc/default/	2m 14s
7.0/ubuntu-20.04/gcc/static/CMD_CXXFLAGS=-std=c++11	2m 14s
7.0/ubuntu-20.04/clang/default/CMD_CXXFLAGS=-std=c++11	2m 6s
7.0/ubuntu-20.04/gcc/default4.10/	2m 49s
7.0/ubuntu-20.04/gcc/default4.9/	2m 52s
7.0/ubuntu-20.04/gcc-8/default/	2m 9s
7.0/ubuntu-20.04/clang/default/	1m 56s
7.0/ubuntu-latest/gcc/default/	2m 19s
	23m 55s

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