[FIX] Workaround for missing TreeExplainer SHAP dimensions

[PrimozGodec]

Issues

• TreeExplainer for XGBClassifier and GradientBoostingClassifier in case of binary classification outputs only explanation for class 1 (skipping class 0). The fix is already a PR in the SHAP library, but it does not look like it will be accepted soon (https://github.com/slundberg/shap/pull/1046).
• explain (for tree explainer) module wrongly imputes SHAP values for classes missing in the training phase. Missing explanations are always appended to the end of the list, which is wrong for cases when the missing type is not the last one.

Changes

• Making a workaround for missing explanation for XGBClassifier and GradientBoostingClassifier.
• fixing imputation
• increasing the SHAP version
• small PyQt6 compatibility fix (transforming RGB to integers)

[codecov-commenter]

Codecov Report

Base: 89.69% // Head: 89.71% // Increases project coverage by +0.01% :tada:

Coverage data is based on head (c941917) compared to base (1b676cd). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #50 +/- ## ========================================== + Coverage 89.69% 89.71% +0.01% ========================================== Files 10 10 Lines 3106 3111 +5 ========================================== + Hits 2786 2791 +5 Misses 320 320 ``` | [Impacted Files](https://codecov.io/gh/biolab/orange3-explain/pull/50?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab) | Coverage Δ | | |---|---|---| | [orangecontrib/explain/explainer.py](https://codecov.io/gh/biolab/orange3-explain/pull/50/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi9leHBsYWluL2V4cGxhaW5lci5weQ==) | `100.00% <100.00%> (ø)` | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab)

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[PrimozGodec]

@VesnaT Python 3.11 test failed since the SHAP library is not ready for Python 3.11. As I saw, there is already PR which needs to be considered.

[PrimozGodec]

/rebase

[PrimozGodec]

/rebase