`DatagramState::drop_oversized` should update `DatagramState::outgoing_total`

[dongcarl]

I could be mistaken, but it seems that DatagramState::outgoing_total is updated every time DatagramState::outgoing is touched, except for in DatagramState::drop_oversized, is there a reason for this?

quinn/quinn-proto/src/connection/datagrams.rs

Lines 147 to 159 in 00df048

	pub(super) fn drop_oversized(&mut self, max_payload: usize) {
	self.outgoing.retain(|datagram| {
	let result = datagram.data.len() < max_payload;
	if !result {
	trace!(
	"dropping {} byte datagram violating {} byte limit",
	datagram.data.len(),
	max_payload
	);
	}
	result
	});
	}

[djc]

Ah, you're right! That does look like a bug -- see proposed trivial fix in #1987.