pdfminer3k Issue breaks pip install/ minecart import

[TomTJarosz]

pdfminer3k was removed from Pip a few days ago. This completely broke pip install minecart, as pdfminer3k is a dependency of minecart. Since then, a different user seems to have published a new pip package under the name pdfminer3k (Old pdfminer3k repo: https://github.com/jaepil/pdfminer3k vs new pdfminer3k repo: https://github.com/canserhat77/pdfminer3k ). This new package seems to be near identical to the old one, but it does not install its dependencies (ply >=3.4). As a results, importing minecart will fail unless you manually install ply into your environment. I have created a PR to use pdfminer for minecart (as apposed to pdfminer3k), which should resolve this issue: #33