fix: datagraph module warning

```python
/home/bioinf/bhklab/radiomics/repos/med-imagetools/src/imgtools/modules/datagraph.py:519: UserWarning: This pattern is interpreted as a regular expression, and has match groups. To actually get the groups, use str.extract.
  self.df_new.edge_type.str.contains(f'(?:{regex_term})', regex=True),

```

i dont think its a breaking change for a fix, just annoying 