crate: prepare for release v0.3.0-alpha.2

Cargo.toml

@@ -1,7 +1,7 @@
 [package]
 name = "rustsbi"
 description = "Minimal RISC-V's SBI implementation library in Rust"
-version = "0.3.0-alpha.1"
+version = "0.3.0-alpha.2"
 authors = [
     "Luo Jia <me@luojia.cc>",
     "Campbell He <hkp18@mails.tsinghua.edu.cn>",
@@ -17,7 +17,7 @@ edition = "2021"
 
 [dependencies]
 riscv = "0.8"
-sbi-spec = "0.0.1"
+sbi-spec = "0.0.2"
 
 [features]
 default = []