fix / hasher generator on docs

[rapcmia]

Update the https://github.com/hummingbot/dashboard/blob/main/INSTALLATION.md#method-1-using-hasher_generate to:

import streamlit_authenticator as st_auth
hashed_password = st_auth.Hasher("YOUR_PLAIN_TEXT_PASSWORD").generate()[0]
print(hashed_password)

steamlit_authenticator seem to have updated and hasher_generate is not supported anymore

[nikspz]

Test performed:

Generated Hashed Password successfully with

python
>>    import streamlit_authenticator as st_auth
>>    hashed_password = st_auth.Hasher("YOUR_PLAIN_TEXT_PASSWORD").generate()[0]
>>    print(hashed_password)

[fer000n]

same problem:

hashed_password = st_auth.Hasher("test").generate()[0]
Traceback (most recent call last):
File "", line 1, in
AttributeError: module 'streamlit_authenticator' has no attribute 'Hasher'