Fix assertion message

[YichiZhang0613]

In azalea/azalea-core/src/bitset.rs, the assertion's message "range.start must be greater than range.end" is wrong. It should be "range.start must be less than or equal to range.end" instead.

/// # Panics
    ///
    /// Panics if the range is invalid (start > end).
    pub fn clear(&mut self, range: Range<usize>) {
        assert!(
            range.start <= range.end,
            "Range ends before it starts; {} must be greater than {}",
            range.start,
            range.end
        );
...

[mat-1]

Thanks :)