refactor: change pdfminer to pdfminer.six

Author: howiezhao

README.md

@@ -1095,7 +1095,7 @@ Inspired by [awesome-php](https://github.com/ziadoz/awesome-php).
     * [xlwings](https://github.com/ZoomerAnalytics/xlwings) - A BSD-licensed library that makes it easy to call Python from Excel and vice versa.
     * [xlwt](https://github.com/python-excel/xlwt) / [xlrd](https://github.com/python-excel/xlrd) - Writing and reading data and formatting information from Excel files.
 * PDF
-    * [PDFMiner](https://github.com/euske/pdfminer) - A tool for extracting information from PDF documents.
+    * [pdfminer.six](https://github.com/pdfminer/pdfminer.six) - Pdfminer.six is a community maintained fork of the original PDFMiner.
     * [PyPDF2](https://github.com/mstamy2/PyPDF2) - A library capable of splitting, merging and transforming PDF pages.
     * [ReportLab](https://www.reportlab.com/opensource/) - Allowing Rapid creation of rich PDF documents.
 * Markdown