community[patch]: support OpenAI whisper base url (#17695)

**Description:** The base URL for OpenAI is retrieved from the
environment variable "OPENAI_BASE_URL", whereas for langchain it is
obtained from "OPENAI_API_BASE". By adding `base_url =
os.environ.get("OPENAI_API_BASE")`, the OpenAI proxy can execute
correctly.

---------

Co-authored-by: Bagatur <baskaryan@gmail.com>

libs/community/langchain_community/document_loaders/parsers/audio.py

@@ -1,4 +1,5 @@
 import logging
+import os
 import time
 from typing import Dict, Iterator, Optional, Tuple
 
@@ -25,10 +26,17 @@ class OpenAIWhisperParser(BaseBlobParser):
     """
 
     def __init__(
-        self, api_key: Optional[str] = None, *, chunk_duration_threshold: float = 0.1
+        self,
+        api_key: Optional[str] = None,
+        *,
+        chunk_duration_threshold: float = 0.1,
+        base_url: Optional[str] = None,
     ):
         self.api_key = api_key
         self.chunk_duration_threshold = chunk_duration_threshold
+        self.base_url = (
+            base_url if base_url is not None else os.environ.get("OPENAI_API_BASE")
+        )
 
     def lazy_parse(self, blob: Blob) -> Iterator[Document]:
         """Lazily parse the blob."""
@@ -51,11 +59,13 @@ class OpenAIWhisperParser(BaseBlobParser):
 
         if is_openai_v1():
             # api_key optional, defaults to `os.environ['OPENAI_API_KEY']`
-            client = openai.OpenAI(api_key=self.api_key)
+            client = openai.OpenAI(api_key=self.api_key, base_url=self.base_url)
         else:
             # Set the API key if provided
             if self.api_key:
                 openai.api_key = self.api_key
+            if self.base_url:
+                openai.base_url = self.base_url
 
         # Audio file from disk
         audio = AudioSegment.from_file(blob.path)