release v0.26.0

Release notes:

• Update github action for checkout, upload-artifact and setup-python from version 2 to 3 by @gaugup in #515
• Add flake8-pytest-style to linting by @gaugup in #512
• Improve the documentation website for interpret-community and update the main readme by @imatiach-msft in #518
• fix aggregating sparse multiclass explanations to global in global-only streaming with batches mode by @imatiach-msft in #519
• improve readme by only leaving high-level overview and move more sections to the website with more details by @imatiach-msft in #520
• add more documentation to interpret-community website, including a contributing guide by @imatiach-msft in #522
• fix gated build due to protobuf dependency error by @imatiach-msft in #524
• rename master branch to main in interpret-community by @imatiach-msft in #525
• fix zero importances for very small data when using mimic explainer with lightgbm surrogate model by @imatiach-msft in #523
• update interpret-community to ml-wrappers 0.2.0 by @imatiach-msft in #527

Full Changelog: v0.25.0...v0.26.0