ci(workflow): pin cargo-tarpaulin to 0.35.2 --locked (#42)

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: nanotaboada

.github/workflows/rust-ci.yml

@@ -114,7 +114,7 @@ jobs:
           key: ${{ runner.os }}-cargo-tarpaulin-${{ hashFiles('**/Cargo.lock') }}
 
       - name: Install cargo-tarpaulin
-        run: cargo install cargo-tarpaulin
+        run: cargo install cargo-tarpaulin --version 0.35.2 --locked
 
       - name: Generate coverage report
         run: cargo tarpaulin --out xml