pa-bin does not work with lowercase bases [bug]

[samuell]

How to reproduce

1. Create a file lowercase.fa with content:

>seq1
acgt
>seq2
acg

2. Run pa-bin on it:

pa-bin --input lowercase.fa --output lowercase.csv

Expected output

Done:   1

(This is the case for a file with the same content but uppercase, so):

>seq1
ACGT
>seq2
ACG

Actual output

Done:   0
thread 'main' panicked at /home/<snip>/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/bio-1.3.0/src/alphabets/mod.rs:264:37:
Unexpected character.
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace