Removed the unusued function hydro_reion_heating()

src/hydro/PressureEnergy/hydro.h

@@ -910,22 +910,4 @@ hydro_set_init_internal_energy(struct part *p, float u_init) {
 __attribute__((always_inline)) INLINE static void hydro_remove_part(
     const struct part *p, const struct xpart *xp) {}
 
-/**
- * @brief Inputs extra heat to a particle at redshift of reionization
- *
- * We assume a constant density.
- * @param p The particle of interest
- * @param xp The extended particle data
- * @param cosmo Cosmology data structure
- * @param extra_heat The extra internal energy given to the particle.
- */
-__attribute__((always_inline)) INLINE static void hydro_reion_heating(
-    struct part *p, struct xpart *xp, const struct cosmology *cosmo,
-    float extra_heat) {
-
-  const float old_u = xp->u_full * cosmo->a_factor_internal_energy;
-  const float new_u = old_u + extra_heat;
-  xp->u_full = new_u / cosmo->a_factor_internal_energy;
-}
-
 #endif /* SWIFT_PRESSURE_ENERGY_HYDRO_H */