Can't figure out correct format to conver object to datetime

Question

I need to convert a date in a .txt file that looks like '08-abr-19'.

The file is in Spanish so that's why April looks like 'abr' instead of 'apr'

I have tried using several formats as suggested in this site: http://strftime.org/

However, none of them seem to work. The most obvious to me was:

df['a'] = pd.to_datetime(df['a'],format='%d-%b-%y')

I get an error of this type: ValueError: time data '08-abr-19' does not match format '%d-%b-%y' (match)

As a note, I create a dataframe by importing the .txt file. Column 'a' contains the dates in the format I explained in the first line.

Any ideas?