Bug: Using `Candidate::new_tr_keyspend` adds `TXIN_BASE_WEIGHT` twice to the weight

[cygnet3]

In coin_selector.rs, the body of Candidate::new_tr_keyspend looks like this:

pub fn new_tr_keyspend(value: u64) -> Self {
    let weight = TXIN_BASE_WEIGHT + TR_KEYSPEND_SATISFACTION_WEIGHT;
    Self::new(value, weight, true)
}

next, Self::new has this:

pub fn new(value: u64, satisfaction_weight: u64, is_segwit: bool) -> Candidate {
    let weight = TXIN_BASE_WEIGHT + satisfaction_weight;
    Candidate {
        value,
        weight,
        input_count: 1,
        is_segwit,
    }
}

So TXIN_BASE_WEIGHT is counted twice.

To fix, the duplicate TXIN_BASE_WEIGHT should be removed from the body of Candidate::new_tr_keyspend.