build(deps): bump uart_16550 from 0.2.6 to 0.2.7

Bumps [uart_16550](https://github.com/rust-osdev/uart_16550) from 0.2.6 to 0.2.7.
- [Release notes](https://github.com/rust-osdev/uart_16550/releases)
- [Changelog](https://github.com/rust-osdev/uart_16550/blob/master/Changelog.md)
- [Commits](rust-osdev/uart_16550@v0.2.6...v0.2.7)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>

Author: dependabot-preview[bot]

Cargo.lock

@@ -28,4 +28,4 @@ bitflags = "1.2"
 x86_64 = "0.11"
 atomic_refcell = "0.1"
 r-efi = "2.1.0"
-uart_16550 = "0.2.6"
+uart_16550 = "0.2.7"