Remove chardet dependency

[matt-dies-tenet3]

To resolve #673.

Removes the chardet dependency, because:

• chardet is unused
• it was originally added to resolve an issue within pdfminer-six dependencies
• pdfminer-six has since removed the chardet dependency as of pdfminer-six== 20220506
• this package's requirement is pdfminer-six>=20240706

Therefore, chardet is not needed as a dependency of this package. This is helpful to users, who will need to install fewer dependencies now. Furthermore, chardet is LGPL licensed, which is copyleft and requires this package to share the same licensing if it remains a dependency.

[matt-dies-tenet3]

Appears that the tests are only failing for python3.8 during the installation of the library itself, related to the license = "MIT" line within the pyproject.toml. My best guess is that the PEPs that updated how the license is defined within this file didn't make it into python3.8, but have made it into python3.9+. Doesn't seem like this is an issue worth investigating as a part of this PR as it would be out-of-scope.

Other tests are passing elsewhere, as expected! This PR is probably ready for a merge, unless there are other changes that the maintainers would like me to address. If there are, I'm happy to look into them as needed.