Feature: pdfplumber PDF loader with BaseBlobParser (#4552)

# Feature: pdfplumber PDF loader with BaseBlobParser

* Adds pdfplumber as a PDF loader
* Adds pdfplumber as a blob parser.

tests/integration_tests/document_loaders/parsers/test_pdf_parsers.py

@@ -6,6 +6,7 @@ from langchain.document_loaders.base import BaseBlobParser
 from langchain.document_loaders.blob_loaders import Blob
 from langchain.document_loaders.parsers.pdf import (
     PDFMinerParser,
+    PDFPlumberParser,
     PyMuPDFParser,
     PyPDFium2Parser,
     PyPDFParser,
@@ -78,3 +79,8 @@ def test_pypdfium2_parser() -> None:
     """Test PyPDFium2 parser."""
     # Does not follow defaults to split by page.
     _assert_with_parser(PyPDFium2Parser())
+
+
+def test_pdfplumber_parser() -> None:
+    """Test PDFPlumber parser."""
+    _assert_with_parser(PDFPlumberParser())

tests/integration_tests/document_loaders/parsers/test_public_api.py

@@ -8,4 +8,5 @@ def test_parsers_public_api_correct() -> None:
         "PDFMinerParser",
         "PyMuPDFParser",
         "PyPDFium2Parser",
+        "PDFPlumberParser",
     }

tests/unit_tests/document_loader/parsers/test_public_api.py

@@ -8,4 +8,5 @@ def test_parsers_public_api_correct() -> None:
         "PDFMinerParser",
         "PyMuPDFParser",
         "PyPDFium2Parser",
+        "PDFPlumberParser",
     }