devel/rust-analyzer: Update to 2021-10-04

Changes: https://rust-analyzer.github.io/thisweek/2021/09/20/changelog-95.html
Changes: https://rust-analyzer.github.io/thisweek/2021/09/27/changelog-96.html
Changes: https://rust-analyzer.github.io/thisweek/2021/10/04/changelog-97.html