Copydetect

- Feature: the file list and execution parameters are now displayed on the output report (46 by ankostis).
- Feature: improved handling of duplicate hashes. Duplicates are now correctly highlighted on the report and the similarity metric is now simply `overlapping tokens/total token count` instead of `overlapping tokens after removing duplicate fingerprints/number of tokens in unique fingerprints` (48).
- Feature: the default report styling can be overwritten using a custom CSS file provided using the `--css` argument (49 by mikeperalta1).
- Fix: some internal cleanup to how the `CopyDetector` object is configured. There is no impact to the publicly-documented API but code which was referencing parameters passed to this object (e.g., `CopyDetector.noise_t`) may break (47)
- Fix: replaced `pkg_resources` with `importlib.resources` (allowing support for python 3.12). Support for python 3.6 is dropped (52).

- Fix: the "file not ASCII text" warning has been changed to "file not UTF-8" text to reflect the encoding which is actually used.
- Improvement: added a `--encoding` parameter which allows specifying an encoding. If the `chardet` library is installed, `--encoding DETECT` can now be used to automatically detect the encoding of all files

- Fix: corrected an issue introduced by 0.4.4 causing incorrect indexing when there is partial overlap between test and reference files (this could result in crashes or incorrect slice selection on the output report).
- Fix: a "no files found" warning is only displayed if none of the provided extensions are found in a folder rather than printing in individual warning for each missing extension.

- Fix: UTF-8 is explicitly specified when loading the HTML template and saving the output report.
- Improvement: the slice matrix is now implemented as a dictionary instead of an actual matrix and consumes less memory as a result.

CI has also been migrated from Travis to Github Actions

- Fix: corrected a crash which occured when comparing empty slices using the copydetect API.
- Fix: corrected an issue causing certain operating systems to fail for files with non-ASCII characters. UTF-8 is now explicitly specified as the encoding when reading files.

Fix: corrects an issue introduced by version 0.4.0 which caused similarity scores to be lower than they should (see 19 for more information)