Removed SDL_GetRevisionNumber()

Fixes https://github.com/libsdl-org/SDL/issues/6620

include/SDL_version.h

@@ -151,29 +151,6 @@ extern DECLSPEC void SDLCALL SDL_GetVersion(SDL_version * ver);
  */
 extern DECLSPEC const char *SDLCALL SDL_GetRevision(void);
 
-/**
- * Obsolete function, do not use.
- *
- * When SDL was hosted in a Mercurial repository, and was built carefully,
- * this would return the revision number that the build was created from. This
- * number was not reliable for several reasons, but more importantly, SDL is
- * now hosted in a git repository, which does not offer numbers at all, only
- * hashes. This function only ever returns zero now. Don't use it.
- *
- * Before SDL 2.0.16, this might have returned an unreliable, but non-zero
- * number.
- *
- * \deprecated Use SDL_GetRevision() instead; if SDL was carefully built, it
- *             will return a git hash.
- *
- * \returns zero, always, in modern SDL releases.
- *
- * \since This function is available since SDL 3.0.0.
- *
- * \sa SDL_GetRevision
- */
-extern SDL_DEPRECATED DECLSPEC int SDLCALL SDL_GetRevisionNumber(void);
-
 
 /* Ends C function definitions when using C++ */
 #ifdef __cplusplus