Add test for BookChapter repr

[stsewd]

This needs a test

lira/lira/book.py

Lines 73 to 74 in 298679e

	def __repr__(self):
	return f"<BookChapter: {self.title}>"

The test should be in this file

lira/tests/test_book.py

Line 46 in 298679e

class TestBookChapter:

It should be something like this

lira/tests/test_book.py

Line 27 in 298679e

assert str(self.book) == "<Book: Basic Introduction to Python -> example/>"