message: Update CentOS 7 image to use GCC 8
diff: @@ -6,12 +6,12 @@ RUN yum update -y \
  && yum update -y \
  && yum install -y \
  cmake3 \
  - devtoolset-7 \
  - devtoolset-7-libasan-devel \
  - devtoolset-7-libubsan-devel \
  + devtoolset-8 \
  + devtoolset-8-libasan-devel \
  + devtoolset-8-libubsan-devel \
  git \
  make \
  openssl-devel \
  && yum clean all
  -ENV CXX=/opt/rh/devtoolset-7/root/usr/bin/g++
  +ENV CXX=/opt/rh/devtoolset-8/root/usr/bin/g++
  