bootloader update to 0.9.23

After upgrading qemu, bootloader was panicking with an error
`assertion failed: max_phys_addr < (1 << 48) / 512, src\main.rs:294`

Following this discussion rust-osdev/bootloader#264
the version of bootloader has been upgraded.

EuraliOS now fails with a page fault (MALFORMED_TABLE).

Author: bendudson

kernel/Cargo.toml

@@ -8,7 +8,7 @@ name = "stack_overflow"
 harness = false
 
 [dependencies]
-bootloader = { version = "0.9.8", features = ["map_physical_memory"]}
+bootloader = { version = "0.9.23", features = ["map_physical_memory"]}
 volatile = "0.2.6"
 spin = "0.5.2"
 x86_64 = "0.14.2"