Pin rust-toolchain action refs in CI workflows

Author: h4x3rotab

.github/workflows/rust.yml

@@ -20,7 +20,7 @@ jobs:
     - uses: actions/checkout@v4
 
     - name: Install Rust
-      uses: dtolnay/rust-toolchain@master
+      uses: dtolnay/rust-toolchain@1.86
       with:
         toolchain: 1.92.0
         components: clippy, rustfmt

.github/workflows/sdk.yaml

@@ -23,7 +23,7 @@ jobs:
       - uses: actions/checkout@v4
 
       - name: Install Rust
-        uses: dtolnay/rust-toolchain@master
+        uses: dtolnay/rust-toolchain@1.86
         with:
           toolchain: 1.92.0
           components: clippy, rustfmt