get cmake from yum for centos8

dockerbuild/Dockerfile.centos8

@@ -3,14 +3,12 @@ FROM centos:8
 ARG go_pkg_url
 
 RUN yum install -y epel-release
-RUN yum install -y curl git wget openssh-server sudo make rpmdevtools clang gcc-c++ ruby ruby-devel && yum clean all
+RUN yum install -y curl git wget openssh-server sudo make cmake rpmdevtools clang gcc-c++ ruby ruby-devel && yum clean all
 
 RUN curl -s $go_pkg_url -o go.tar.gz && \
     tar -C /usr/local -xzf go.tar.gz && \
     rm go.tar.gz
 
-RUN wget -qO- "https://cmake.org/files/v3.15/cmake-3.15.1-Linux-x86_64.tar.gz" | tar --strip-components=1 -xz -C /usr/local
-
 RUN /usr/bin/ssh-keygen -A
 RUN useradd jenkins-build