Fix nan on DMR effluent parameter selection in section 7

[ericnost]

---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
<ipython-input-19-14a582993ca8> in <module>()
     13 
     14 if visualization.value == "Map":
---> 15   data.show_program_map("2020 DMR Filtered")
     16 elif visualization.value == "Chart":
     17   data.show_chart("2020 DMR Filtered")

/content/ECHO_modules/class.py in show_program_map(self, program, quartiles)
    457       for index, row in map_data.iterrows():
    458         if quartiles == True:
--> 459           r = scale[row["quantile"]]
    460         else:
    461           r = row[aggregator]

KeyError: nan