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"
}