SPEARHEAD bow-tie analysis tool

What's Changed

• Replace SIXS-P example response functions with ideal boxcar response functions.
• Refined the example notebook.
• Added an additional, blue, axis to the right side of the bowtie plots for the response function.
• For the aforementioned reason, removed the grid from the plot displaying the effective geometric factor lines and the response function.
• Minor code improvements.
• Internal updates to the repository (testing, codecoverage, dependabot etc.)

Full Changelog: https://github.com/spearhead-he/bowtie/compare/v0.1.0-alpha...v0.1.0