Add test for CSV with pipe characters

Added a test for CSV conversion handling pipe characters.

Author: Pranav970

packages/markitdown/tests/test_csv_pipe_fix.py

@@ -0,0 +1,23 @@
+import io
+from markitdown.converters._csv_converter import CsvConverter
+from markitdown._stream_info import StreamInfo
+
+# Test CSV with pipe characters
+csv_content = b"""name,description
+John|Doe,Developer|Engineer
+Alice,Manager|Lead"""
+
+converter = CsvConverter()
+stream_info = StreamInfo(extension=".csv", charset="utf-8")
+
+result = converter.convert(
+    io.BytesIO(csv_content),
+    stream_info
+)
+
+print(result.markdown)
+# Output should have escaped pipes:
+# | name | description |
+# | --- | --- |
+# | John\|Doe | Developer\|Engineer |
+# | Alice | Manager\|Lead |