fsoubelet/PyhDToolkit: Release 0.18.0

Release 0.18.0 brings the following changes:

• The pyhdtoolkit.utils._misc module has a new function, ~pyhdtoolkit.utils._misc.add_markers_around_lhc_ip to add MAD-X markers around a given IP in order to increase the resolution of the TWISS calls in the IP vicinity.
• The pyhdtoolkit.utils._misc module has a new function, ~pyhdtoolkit.utils._misc.get_lhc_ips_positions, to determine the longitudinal position (S variable) of LHC IPs from a dataframe.
• The pyhdtoolkit.utils._misc module has a new function, ~pyhdtoolkit.utils._misc.draw_ip_locations, to add labels with the location of LHC IPs to a given ~matplotlib.axes.Axes object.
• The LHC Rigid Waist Shift gallery has been improved, and now shows a visualization of the waist shift and two ways to calculate its value.

• The ~pyhdtoolkit.cpymadtools.orbit.lhc_orbit_variables function does not return a wrong on_phi_IR5 variable anymore.

• The dependency on matplotlib has been pinned to <3.5 to avoid issues with the documentation plot style, to be fixed later on.
• The bibliography file for the package's documentation has been cleaned up.
• The Github icon in the documentation pages now redirects to the proper pages.
• The documentation for the ~pyhdtoolkit.maths.nonconvex_phase_sync has been improved.
• Some additional files necessary for the documentation additions are now included in the repo, but not the package.

• Niceties and improved documentation by @fsoubelet in https://github.com/fsoubelet/PyhDToolkit/pull/80

Full Changelog: https://github.com/fsoubelet/PyhDToolkit/compare/0.17.0...0.18.0