message: update required cmake version
diff: @@ -21,7 +21,7 @@ env:
  - DEPS_DIR=${TRAVIS_BUILD_DIR}/deps
  - BOOST_URL="http://sourceforge.net/projects/boost/files/boost/1.63.0/boost_1_63_0.tar.gz"
  - BOOST_VERSION="1_63_0"
  - - CMAKE_VERSION="3.6.3"
  + - CMAKE_VERSION="3.12.0"
  cache:
  directories:
  @@ -228,7 +228,7 @@ before_install:
  - |
  if [ "${TRAVIS_OS_NAME}" == "linux" ]; then
  if [ -z "$(ls -A ${DEPS_DIR}/cmake-${CMAKE_VERSION}/cached)" ]; then
  - CMAKE_URL="https://cmake.org/files/v3.6/cmake-${CMAKE_VERSION}-Linux-x86_64.tar.gz"
  + CMAKE_URL="https://cmake.org/files/v3.12/cmake-${CMAKE_VERSION}-Linux-x86_64.tar.gz"
  mkdir -p ${DEPS_DIR}/cmake-${CMAKE_VERSION}
  travis_retry wget --no-check-certificate --quiet -O - "${CMAKE_URL}" | tar --strip-components=1 -xz -C ${DEPS_DIR}/cmake-${CMAKE_VERSION}
  touch ${DEPS_DIR}/cmake-${CMAKE_VERSION}/cached
  