Updated Cargo.toml

The old Cargo.toml was a bit out-of-date. This commit adds the RISC-V
Team to the authors list, as well as bumping the version and edition to
1.59.0 and 2021.

Cargo.toml

@@ -2,6 +2,7 @@
 authors = [
     "The Cortex-M Team <cortex-m@teams.rust-embedded.org>",
     "Jorge Aparicio <japaricious@gmail.com>",
+    "The RISC-V Team <risc-v@teams.rust-embedded.org>",
 ]
 description = "Semihosting for RISCV processors"
 documentation = "https://docs.rs/riscv-semihosting"
@@ -12,7 +13,8 @@ name = "riscv-semihosting"
 readme = "README.md"
 repository = "https://github.com/riscv-rust/riscv-semihosting"
 version = "0.0.1"
-edition = "2018"
+edition = "2021"
+rust-version = "1.59.0"
 
 [features]
 default = ["jlink-quirks"]