Upgrade MSRV to 1.77 , and rusqlite to 0.32.1

Rusqlite 0.32.1 requires Rust 1.77. This MR upgrades both.

Our MSRV policy allows us to upgrade to this version (released 6 months and 4 days ago) so long as we have a good reason; I claim that upgrading rusqlite is such a reason.

Please do not merge until we have gathered consensus on the MSRV 1.77 update: So far, @opara has given a +1 here, but I'd like a couple more "sure, go aheads" before we merge.