Depend on libignition-utils1-dev

[scpeters]

Nightly builds have been failing since gazebosim/gz-math#299 was merged

• https://build.osrfoundation.org/job/ign-math7-debbuilder/325/

CMake Warning at /usr/share/cmake/ignition-cmake2/cmake2/IgnUtils.cmake:189 (find_package):
  By not providing "Findignition-utils1.cmake" in CMAKE_MODULE_PATH this
  project has asked CMake to find a package configuration file provided by
  "ignition-utils1", but CMake did not find one.

  Could not find a package configuration file provided by "ignition-utils1"
  (requested version 1.0) with any of the following names:

    ignition-utils1Config.cmake
    ignition-utils1-config.cmake

  Add the installation prefix of "ignition-utils1" to CMAKE_PREFIX_PATH or
  set "ignition-utils1_DIR" to a directory containing one of the above files.
  If "ignition-utils1" provides a separate development package or SDK, be
  sure it has been installed.
Call Stack (most recent call first):
  CMakeLists.txt:43 (ign_find_package)

This should fix it.

[scpeters]

testing https://build.osrfoundation.org/job/ign-math7-debbuilder/329/