[CMake] Make Python3 required dependency

we basically use it everywhere.

Author: lukaszstolarczuk

CMakeLists.txt

@@ -18,7 +18,7 @@ if(CMAKE_SYSTEM_NAME STREQUAL Darwin)
   set(CMAKE_FIND_FRAMEWORK NEVER)
 endif()
 
-find_package(Python3 COMPONENTS Interpreter)
+find_package(Python3 COMPONENTS Interpreter REQUIRED)
 
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_STANDARD_REQUIRED YES)

README.md

@@ -77,6 +77,7 @@ Tools can be acquired via instructions in [third_party](/third_party/README.md).
 Required packages:
 - C++ compiler with C++17 support
 - [CMake](https://cmake.org/) >= 3.14.0
+- Python v3.6.6 or later
 
 For development and contributions:
 - clang-format-15.0 (can be installed with `python -m pip install clang-format==15.0.7`)