CMake 3.2.3 or later to use AppleClang on OSX

GoogleTest uses CMake compile feature detection.

.travis.yml

@@ -44,7 +44,8 @@ matrix:
     - name: CMake validation on OSX
       os: osx
       osx_image: xcode11.3
-      env: *CMAKE_VERSION_LIST
+      env:
+      - CMAKE_VERSION: '"3.16.2 3.15.6 3.14.7 3.13.5 3.12.4 3.11.4 3.10.3 3.9.6 3.8.2 3.7.2 3.6.3 3.5.2 3.4.3 3.3.2 3.2.3"'
       script:
       - |
         cd ./build

README.md

@@ -53,7 +53,7 @@ contributing any changes that were necessary back to this project to benefit the
 ## Building the tests
 To build the tests, you will require the following:
 
-* [CMake](http://cmake.org), version 3.1.3 or later to be installed and in your PATH.
+* [CMake](http://cmake.org), version 3.1.3 (3.2.3 for AppleClang) or later to be installed and in your PATH.
 
 These steps assume the source code of this repository has been cloned into a directory named `c:\GSL`.