red sandstone texture broken and fix to it

fix to a visual bug related to red sandstone stairs,just replace the current "code" with the one below

"red_sandstone_stairs": {
"isotropic":

{ "up": true, "down": true }

,
"blockshape": "stairs",
"textures":

{ "up": "redsandstone_top", "down": "redsandstone_bottom", "side": "redsandstone_side" }