Release 0.8.0

What's new?

Features:

• Implement contains method for StringList;
• Implement IndexList with __init__, __repr__, __str__, __back__ and to_list methods;
• Method to convert BooleanList to IndexList;
• Implement get_by_indexes method;
• Implement select function and case method for StringList.

Benchmark:

• Implement Benchmarker class to compare performances between ulist and numpy;
• Write benchmark scripts for Integer dtype including add, counter, mul, max, equal, unique, sum and sort methods;
• Write benchmark scripts for Float dtype including add, mul, max, less_than, sum and sort methods;
• Write benchmark scripts for Boolean dtype including all, and_, any, not_, or_ methods;
• Write benchmark scripts for String dtype including contains, counter and equal methods.

Doc:

• Update the examples of Readme.md;
• Add ulist's introduction and features in Readme.md;
• Markdown doc to save the benchmarking core;
• Add performance paragraph in Readme.md;

Misc:

• Upgrade the dependency PYO3 to v0.16.1;
• Make get method as a "safe" method;
• Github action to calculate benchmarking core.