How to show box plot y-axis values in Matplotlib

Question

I have made a function that draws two boxplots side by side based on some input values. The code works fine but I cannot see any numbers on the y axis, it just draws the plots with no reference scale. Does anyone know how to get the y axis values displayed?

Btw I am quite knew to python so I am sure I could have written the function better.

#Define a function where you put the results of the regression. Put in the low and upper 
#confidence interval, 
# and it will back-transform from square root and then create a boxplot diagram 
def boxdata(conf_low,conf_high, conf_low_snus, conf_high_snus): 
  name = {}
  confidence_high = (conf_high**2)
  confidence_low = (conf_low**2)
  whislo = (confidence_low-(1.5*(confidence_high-confidence_low)))
  whishi = (confidence_high+(1.5*(confidence_high-confidence_low)))
  confidence_high_snus = (conf_high_snus**2)
  confidence_low_snus = (conf_low_snus**2)
  whislo_snus = (confidence_low_snus-(1.5*(confidence_high_snus-confidence_low_snus)))
  whishi_snus = (confidence_high_snus +(1.5*(confidence_high_snus-confidence_low_snus)))
  data_1 =  {
        'label' : 'No',
        'whislo': whislo,    # Bottom whisker position calculated as q1 - 1.5*(q3-q1) in this 
        'q1'    : confidence_low,    # First quartile (25th percentile)
        'med'   : "",    # Median         (50th percentile)
        'q3'    : confidence_high,    # Third quartile (75th percentile)
        'whishi': whishi,    # Top whisker position calculated as q3 + 1.5*(q3-q1)
        'fliers': [0]        # Outliers
    }
  data_2 =  {
        'label' : 'Yes',
        'whislo': whislo_snus,    # Bottom whisker position calculated as q1 - 1.5*(q3-q1) in 
        'q1'    : confidence_low_snus,    # First quartile (25th percentile)
        'med'   : "",    # Median         (50th percentile)
        'q3'    : confidence_high_snus,    # Third quartile (75th percentile)
        'whishi': whishi_snus,    # Top whisker position calculated as q3 + 1.5*(q3-q1)
        'fliers': [0]        # Outliers
    }
  data_3 = [data_1, data_2] #Makes a list of values so that you can plot them together
  fig, ax = plt.subplots() # Initiates an empty plot 
  ax.set(ylabel="Concentration") #Sets a label on the y axes
  ax.set_ylim(ymin = 10, ymax = 100) #Define the limits of y axis (min/max)
  ax.set_title("Concentration")
  ax.bxp(data_3) #, showfliers=False, widths=0.5) # Draws the plot from the data provided
  plt.savefig("boxplot.png")
  plt.close()

boxdata(5.729958,6.306493,5.2241404,5.8006754)