"selenium" package is not added to "requirements.txt

local libraries are not added to requirements.txt
Output of the pip freeze command:
```
...
selenium==4.2.0
...
```
The only file `test.py` in the folder `test`
test.py:
```
import selenium
```
At the command `pipreqs --use-local test` `requirements.txt` empty

Reproduce the report with the test/test.py example and the command pipreqs --use-local test, then inspect how the import is detected and how requirements.txt is generated. Done means the generated requirements.txt includes selenium for this local import case.

Written by the indexing model from the issue text.