Uptick cmake_minimum_required

When building you see:

```
CMake Deprecation Warning at gFTL-shared/CMakeLists.txt:1 (cmake_minimum_required):
  Compatibility with CMake < 3.5 will be removed from a future version of
  CMake.

  Update the VERSION argument <min> value or use a ...<max> suffix to tell
  CMake that the project does not need compatibility with older versions.

```

so we uptick the version to something a bit newer to remove that.

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.0)
+cmake_minimum_required(VERSION 3.12)
 
 # Note: the CMake project name is spelled slightly different than the
 # git project.  This is to allow superprojects to use an environment

ChangeLog.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added `-quiet` flag for NAG Fortran
 - Remove `macos-11` and `macos-12` from GitHub Actions, move to use `macos-13` and `macos-14`
 - Add Ubuntu 24 to CI that has `gfortran-13`. Remove `gfortran-13` test from ubuntu 22
+- Up `cmake_minimum_required`
 
 ## [1.8.0] - 2024-03-03