ci(supply-chain): Install Rust toolchain in supply-chain workflow

.gitea/workflows/supply-chain.yml

@@ -47,6 +47,11 @@ jobs:
         with:
           persist-credentials: false
 
+      - name: Install Rust toolchain
+        uses: actions-rust-lang/setup-rust-toolchain@ecabd13d1c56bd1345c230e542e9144811ad706f # v2
+        with:
+          cache: false
+
       - name: Install cargo-deny
         run: |
           set -euo pipefail