Include upper boundary of regression ranges (and add a legacy option for pythonic ranges).

[smoia]

Closes None

Now regression ranges will include the upper boundary, i.e. might return one lag more if the specified max lag is a multiple of the lag step.
However, this behavior can be switched off using the flag --legacy

Proposed Changes

• Regression ranges include the upper boundary
• If instead pythonic ranges are preferred, they can be used with the --legacy option.

Change Type

• bugfix (+0.0.1)
• minor (+0.1.0)
• major (+1.0.0)
• refactoring (no version update)
• test (no version update)
• infrastructure (no version update)
• documentation (no version update)
• other

Checklist before review

• I added everything I wanted to add to this PR.
• [Code or tests only] I wrote/updated the necessary docstrings.
• [Code or tests only] I ran and passed tests locally.
• [Documentation only] I built the docs locally.
• My contribution is harmonious with the rest of the code: I'm not introducing repetitions.
• My code respects the adopted style, especially linting conventions.
• The title of this PR is explanatory on its own, enough to be understood as part of a changelog.
• I added or indicated the right labels.

• I added information regarding the timeline of completion for this PR.

• Please, comment on my PR while it's a draft and give me feedback on the development!

[smoia]

🚀 PR was released in 0.8.0 🚀