[CMake] Raise minimum required CMake version to 3.10

To avoid this warning:

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

Author: guitargeek

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.9 FATAL_ERROR)
+cmake_minimum_required(VERSION 3.10 FATAL_ERROR)
 
 project(roottest)