refactor: loader chunker typing (#324)

embedchain/loaders/pdf_file.py

@@ -1,9 +1,10 @@
 from langchain.document_loaders import PyPDFLoader
 
+from embedchain.loaders.base_loader import BaseLoader
 from embedchain.utils import clean_string
 
 
-class PdfFileLoader:
+class PdfFileLoader(BaseLoader):
     def load_data(self, url):
         """Load data from a PDF file."""
         loader = PyPDFLoader(url)