Deprecate action

Author: AS1100K

README.md

@@ -8,6 +8,12 @@
 
 GitHub actions for installing rust toolchain
 
+> [!WARNING] This action has been deprecated. It is recommended to use `rustup`,
+> which is pre-installed on GitHub-hosted runners, or alternatively, consider
+> using the `dtolnay/rust-toolchain` action available at
+> https://github.com/dtolnay/rust-toolchain for better support and
+> functionality.
+
 ## Example Workflow
 
 ```yml

badges/coverage.svg

@@ -9,6 +9,9 @@ import { exec } from '@actions/exec'
  */
 export async function run(): Promise<void> {
   try {
+    core.error(
+      'This action has been deprecated. It is recommended to use `rustup`, which is pre-installed on GitHub-hosted runners, or alternatively, consider using the `dtolnay/rust-toolchain` action available at https://github.com/dtolnay/rust-toolchain for better support and functionality.'
+    )
     const platform: Platform = await core.platform.getDetails()
 
     const rust_toolchain: string = core.getInput('toolchain', {