fix CI build (rustup)

packaging/alpine/local/greptimedb/APKBUILD

@@ -9,7 +9,6 @@ license="Apache-2.0"
 depends="ca-certificates"
 makedepends="
 	binutils
-	cargo
 	clang
 	cmake
 	coreutils
@@ -22,7 +21,7 @@ makedepends="
 	perl
 	protobuf
 	protobuf-dev
-	rust
+	rustup
 	zlib-dev
 	zlib-static
 	zstd-dev
@@ -31,12 +30,19 @@ makedepends="
 options="net"
 source="$pkgname-$pkgver.tar.gz::https://github.com/GreptimeTeam/greptimedb/archive/refs/tags/v$pkgver.tar.gz"
 
+_rust_toolchain="nightly-2026-03-21"
 export CARGO_HOME="$srcdir/cargo"
+export RUSTUP_HOME="$srcdir/rustup"
 export CARGO_BUILD_JOBS="${CARGO_BUILD_JOBS:-2}"
 export LIBRARY_PATH="/usr/lib"
 
+prepare() {
+	default_prepare
+	rustup toolchain install --profile minimal --no-self-update "$_rust_toolchain"
+}
+
 build() {
-	cargo build \
+	rustup run "$_rust_toolchain" cargo build \
 		--release \
 		--locked \
 		--bin greptime \