How to use the local rustc first instead of the default download

In my project, I introduce rules_rust:
```bash
http_archive(
name = "rules_rust",
sha256 = "4a9cb4fda6ccd5b5ec393b2e944822a62e050c7c06f1ea41607f14c4fdec57a2",
urls = ["https://github.com/bazelbuild/rules_rust/releases/download/0.25.1/rules_rust-v0.25.1.tar.gz"],
)
load("@rules_rust//rust:repositories.bzl", "rules_rust_dependencies", "rust_register_toolchains")

rules_rust_dependencies()

rust_register_toolchains(
# https://doc.rust-lang.org/edition-guide/editions/
edition = "2021",
)
```
But when I bazel buid, I find that rustc will be downloaded first.
```bash
Loading:
Fetching repository @cargo_crate; Restarting.
Fetching https://static.rust-lang.org/dist/rustc-1.70.0-x86_64-unknown-linux-gnu.tar.gz; 657.2 KiB (672,974B)
root@xx:$ rustc --version
rustc 1.66.1 (90743e729 2023-01-10) (built from a source tarball)
```
Because rust_register_toolchains contains the urls parameter:

I tried adding the local version to versions, but it still downloads:
```bash
diff --git a/WORKSPACE b/WORKSPACE
index e067840..3ae159f 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -14,6 +14,9 @@ rules_rust_dependencies()
rust_register_toolchains(
# https://doc.rust-lang.org/edition-guide/editions/
edition = "2021",
+ versions = [
+ "1.66.1",
+ ],
)

load("@rules_rust//crate_universe:repositories.bzl", "crate_universe_dependencies")
```
```bash
Loading:
Fetching repository @cargo_crate; Restarting.
Fetching https://static.rust-lang.org/dist/rustc-1.66.1-x86_64-unknown-linux-gnu.tar.gz; 6.0 MiB (6,299,648B)
root@xx:$ rustc --version
rustc 1.66.1 (90743e729 2023-01-10) (built from a source tarball)
```
Is there any way to prohibit the download and use the local rustc directly?