This is the official core profile header, but it includes up to latest GL 4.5 version + some extensions: https://github.com/KhronosGroup/O...ry/blob/master/api/GL/glcorearb.h
It is autogenerated from these xml files: https://github.com/KhronosGroup/OpenGL-Registry/tree/master/xml
You can parse these xml files yourself and generate only what you want (only specific version, no extensions, or something other). It includes pdf documentation describing xml format, but it is very simple.
There is glad generator that will generate only what you choose: http://glad.dav1d.de/
It will produce C header, and optionally very tiny loader that requires you to provide actual loading function.