centre palette for plotting - Seaborn

I'm hoping to centre a seaborn palette using a diverting colormap. Specifically, I want zero to signify the divergence. However, may values aren't distributed evenly. So the min and max values aren't the same distance from 0. As such, the palette doesn't align. I'm still hoping to use the same palette colors but centre the divergence at 0.

df = pd.DataFrame({ 
    'Val' : ['A','A','A','A','A','A','A','A','A','A','A','A'],                  
    'A_1' : [-5, 2, 3, 4, 5, 7, 1, -4, -2, 6, -1, 0],                      
        })

g = sns.FacetGrid(df, 
                  col = 'Val', 
                  hue = 'A_1',                               
                  aspect = 1,
                  height = 5, 
                  palette = 'BrBG',
                  sharex = False)


g.map(sns.swarmplot, 'Val', 'A_1')