deps: follow openkal 0.7.0

规范新增 `openkal.random`,版本升到 0.7.0。CI 的版本同步门要求实现与规范
同步声明 —— 它的诊断说得很准:「Nothing is wrong with either; they are not
in step.」

Author: Sunrisepeak

mcpp.toml

@@ -15,7 +15,7 @@ authors     = ["mcpplibs"]
 repo        = "https://github.com/mcpplibs/openkal-musl"
 
 [dependencies]
-openkal = "0.6.0"
+openkal = "0.7.0"
 
 # An ordinary consumer of openkal declares the specification and leaves the
 # choice of implementation to whoever builds the program, which is what the