CMake warning one Homebrew CI

[azeey]

Environment

• OS Version: Homebrew
• Source or binary build? gz-plugin2

Description

• Expected behavior: No CMake warnings
• Actual behavior: Two CMake warnings are generated on CI

One is tracked by: gazebosim/gz-cmake#461

The other seems to be a gz-plugin issue

CMake Deprecation Warning at CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.10 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value.  Or, use the <min>...<max> syntax
  to tell CMake that the project requires at least <min> but has been updated
  to work with policies introduced by <max> or earlier.

gz-plugin/CMakeLists.txt

Line 1 in 0e088d1

cmake_minimum_required(VERSION 3.5.1 FATAL_ERROR)

[scpeters]

increasing the minimum required cmake version in #162

[scpeters]

fixed by #162