Does the GoG version of SC2 add a changelog or something so the user can adjust the frame rate?

Star Control 2 is an old DOS game. All DOS games ran at a fixed refresh rate (60 or 70Hz).
So, not to confuse or get too technical, could say that was a limit of DOS games for frame rate as well, but it could go well below this (30 or 35 fps in some cases, like original DOOM was designed to run at for example... 1/2 refresh).

To run DOS games these days everyone uses DOSBox, including GoG.
DOSBox uses "cycles" to emulate instructions per time interval. Though this is NOT fps, this can slow or speed up how the game runs.
In the conf file for SC2 (dosboxSC2.conf) will be a cycles setting. It is set to 5000 in SC2 by default.
While in the game you can push Control-F11 to lower cycles or Control-F12 to increase cycles.
Or you can edit the cycles option to any number other than 5000 or "auto" or "max" (be smart, raise it 1000-2000 at a time, or maybe try 10000, then run game and see how it works).

Note that SC2 is a simpler older DOS game and does not likely need a lot of cycles to run at best performance.
Also note that increasing cycles can have detrimental effects on sound quality or possibly game logic in some DOS games.