text: Title: panel.chat.langchain Import recursion error
  Body: The new version, 1.5.0, introduces a recursive import caused by this change https://github.com/holoviz/panel/commit/d0744c50c66866396272e056282c3df38f33ecb9#diff-3e786c7bf61e242b5ec4094db9bb91fab89546aadfa12ed11b56ca0c2a142f71R56. `import_module` protected against this.
  
  #### ALL software version info
  (this library, plus any other relevant software, e.g. bokeh, python, notebook, OS, browser, etc should be added within the dropdown below.)
  
  <details>
      <summary>Software Version Info</summary>
  
  ```plaintext
  1.5.0    
  ```    
  </details>
  
  #### Description of expected behavior and the observed behavior
  
  #### Complete, minimal, self-contained example code that reproduces the issue
  
  ```python
  import panel
  panel.chat.langchain
  RecursionError: maximum recursion depth exceeded
  ```