Language error when using ElectrumV1MnemonicDecoder
When I try to use the _ElectrumV1MnemonicDecoder(my_mnemonic)_ class, I get the error
`TypeError: Language is not an enumerative of Bip39Languages`

I also tried with a newly generated mnemonic:
```
v1_standard_mnemonic = ElectrumV1MnemonicGenerator().FromWordsNumber(ElectrumV1WordsNum.WORDS_NUM_12)
my_mnemonic = v1_standard_mnemonic.ToStr()
ElectrumV1MnemonicDecoder(my_mnemonic)
```
If I understood the description of the _ElectrumV1MnemonicDecoder_, feeding it a mnemnonic string should be sufficient. 
Am I overlooking something?
