Why I try to run pip install . in the DPR directory, it returns the following error:

`Processing /export/home/conversational_retrieval/DPR
Preparing metadata (setup.py) ... error
error: subprocess-exited-with-error

× python setup.py egg_info did not run successfully.
│ exit code: 1
╰─> [14 lines of output]
error: Multiple top-level packages discovered in a flat-layout: ['dpr', 'conf'].

  To avoid accidental inclusion of unwanted files or directories,
  setuptools will not proceed with this build.
  
  If you are trying to create a single distribution with multiple packages
  on purpose, you should not rely on automatic discovery.
  Instead, consider the following options:
  
  1. set up custom discovery (`find` directive with `include` or `exclude`)
  2. use a `src-layout`
  3. explicitly set `py_modules` or `packages` with a list of names
  
  To find more information, look for "package discovery" on setuptools docs.
  [end of output]

note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─> See above for output.

note: This is an issue with the package mentioned above, not pip.`