ci: install x86_64-unknown-none target

Fix CI newlib user-lib build failure (E0463: can't find crate for core) by installing the rust target required by builders/newlib.rs.

Also declare both targets in rust-toolchain.toml for local parity.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: minto-dane

.github/workflows/ci.yml

@@ -33,7 +33,7 @@ jobs:
         uses: dtolnay/rust-toolchain@nightly
         with:
           components: rust-src, llvm-tools, rustfmt
-          targets: x86_64-unknown-uefi
+          targets: x86_64-unknown-uefi,x86_64-unknown-none
 
       - name: Cache Rust build artifacts
         uses: Swatinem/rust-cache@v2

rust-toolchain.toml

@@ -1,3 +1,4 @@
 [toolchain]
 channel = "nightly"
 components = ["rust-src", "llvm-tools"]
+targets = ["x86_64-unknown-uefi", "x86_64-unknown-none"]