Making the grid lines tilted in UTM projection, while the frame remains not tilted

Hello, I’m new to PyGMT and trying to create a basemap using a UTM projection. I need the coordinate labels to be in geographic degree-minutes, so the geographic grid lines will be slightly tilted. When I use PyGMT, both the grid lines and the frame are tilted (attached figure).

> x_min_geo, y_min_geo, x_max_geo, y_max_geo = 91.9323705965323, 36.95416334549905, 92.06799033233855, 37.02722411685934
> region = [x_min_geo, x_max_geo, y_min_geo, y_max_geo]
> fig = pygmt.Figure()
> with pygmt.config(MAP_SCALE_HEIGHT="7p"):
>     fig.basemap(region=region, projection="U46R/12c", frame="ag")
> fig.show(width=1000)

My question, how can I make the geographic grid lines and ticks tilted while keeping the frame itself not tilted?

Thanks