Updated approx implementation to exclude sets and Documentation cleanup for approx

[fumedev]

CHANGED

• Updated the __repr__ method in the ApproxSequencelike class to specifically check for sequence types (e.g., list, tuple) and exclude sets. Added a TypeError raise if a set is passed to approx.
• Modified the _yield_comparisons method to raise a TypeError if a set is passed to approx, ensuring pytest.approx() does not support sets as input.
• Created a new file at doc/en/usage/assertions.rst to update the documentation for approx and removed any mention that implies support for sets, clarifying that approx only supports sequence types like lists and tuples with ordered elements.