release: 0.5.4

The branch carried 0.5.3, which is the version on `main` and the version
already in the index. Following openkal 0.7.0 changes what this package
declares, and on two of these repositories it also adds an interface, so
the content behind that number is no longer the content published under
it.

openkal takes a minor bump for a new interface and an implementation
following it takes a patch bump --- the shape of 0.5.2 → 0.6.0 with
0.5.2 → 0.5.3 beneath it.

Author: Sunrisepeak

mcpp.toml

@@ -1,7 +1,7 @@
 [package]
 namespace   = "mcpplibs"
 name        = "openkal-linux"
-version     = "0.5.3"
+version     = "0.5.4"
 description = "The reference implementation of openkal for Linux, written on the kernel's own system-call interface so that it can be placed beneath a C library as well as above one."
 license     = "Apache-2.0"