I use a code generator plugin to generate the server stub from the OpenAPI specifications.
I want to know if I should commit the generated code to version control.
In general, yes.
The reasoning is simple: if I'm a downstream user of your code—that is, I want to merely include your library as a dependency or build your application,—there is no point in creating additional burden on me for building your code; I should be able to merely go build/go install your code and call it a day.
If, instead, I intend to actually develop your code—either with the intent to have my changes included upstream or for maintaining these changes unpublished—it's perfectly OK to require me to regenerate certain files where it is required.