Update to PSPDFKit 5.1.1 (#40)

* Update to 5.1.1

* Apply suggestions from code review

Co-Authored-By: davidschreiber <davidschreiber@users.noreply.github.com>

Update plugin for PSPDFKit 4.3.0 (#29)

* Add new configuration options

* Add missing dependencies

* Bump plugin versions

* Update README.md

Merge pull request #21 from PSPDFKit/rad/document-password

Add the ability to pass the document's password

Merge pull request #11 from PSPDFKit/julian/3.1.0

Update plugin for usage with PSPDFKit 3.1.0

Chore: Bump version in <plugin> tag to 2.3.3

Chore: Bump plugin version to 2.0.0