Fixed PermissionError on windows (#6170)

Fixed PermissionError that occurred when downloading PDF files via http
in BasePDFLoader on windows.

When downloading PDF files via http in BasePDFLoader, NamedTemporaryFile
is used.
This function cannot open the file again on **Windows**.[Python
Doc](https://docs.python.org/3.9/library/tempfile.html#tempfile.NamedTemporaryFile)

So, we created a **temporary directory** with TemporaryDirectory and
placed the downloaded file there.
temporary directory is deleted in the deconstruct.

Fixes #2698

#### Who can review?

Tag maintainers/contributors who might be interested:

  - @eyurtsev
  - @hwchase17

langchain/document_loaders/pdf.py

@@ -62,15 +62,17 @@ class BasePDFLoader(BaseLoader, ABC):
                 )
 
             self.web_path = self.file_path
-            self.temp_file = tempfile.NamedTemporaryFile()
-            self.temp_file.write(r.content)
-            self.file_path = self.temp_file.name
+            self.temp_dir = tempfile.TemporaryDirectory()
+            temp_pdf = Path(self.temp_dir.name) / "tmp.pdf"
+            with open(temp_pdf, mode="wb") as f:
+                f.write(r.content)
+            self.file_path = str(temp_pdf)
         elif not os.path.isfile(self.file_path):
             raise ValueError("File path %s is not a valid file or url" % self.file_path)
 
     def __del__(self) -> None:
-        if hasattr(self, "temp_file"):
-            self.temp_file.close()
+        if hasattr(self, "temp_dir"):
+            self.temp_dir.cleanup()
 
     @staticmethod
     def _is_valid_url(url: str) -> bool: