Replace CoinAbs by std::abs #215

Job	Run time
Run tests (ubuntu-20.04, true, ADD_CXXFLAGS=-fvisibility=hidden, sudo apt install -y -qq gfortran...	4m 27s
Run tests (ubuntu-20.04, false, ADD_CXXFLAGS=-fvisibility=hidden, sudo apt install -y -qq gfortra...	3m 53s
Run tests (ubuntu-22.04, true, ADD_CXXFLAGS=-fvisibility=hidden, sudo apt install -y -qq gfortran...	4m 1s
Run tests (ubuntu-22.04, false, ADD_CXXFLAGS=-fvisibility=hidden, sudo apt install -y -qq gfortra...	3m 55s
Run tests (macos-13, false, CC=clang OSX=13, brew install metis bash)	5m 15s
Run tests (macos-13, false, CC=gcc-13 CXX=g++-13 OSX=13 ADD_CXXFLAGS=-Wl,-ld_classic, brew instal...	6m 23s
Run tests (macos-14, false, CC=gcc-13 CXX=g++-13 OSX=14 ADD_CXXFLAGS=-Wl,-ld_classic, brew instal...	3m 14s
	31m 8s

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