Bug for replace_placeholder

[jlim262]

If yaml has a configuration as below,
in_path: "text2emospch/input/sentiment-extraction"
transformer_path: "{in_path}/bert-base-uncased/"

Expected behavior

> print(config['transformer_path'])
text2emospch/input/sentiment-extraction/bert-base-uncased

Actual behavior

> print(config['transformer_path'])
{in_path}/bert-base-uncased

BuilT version
v0.0.4

Python version (e.g. python -version)
3.7