Add TODO comment

Author: ipapandinas

.github/workflows/coverage.yaml

@@ -43,6 +43,7 @@ jobs:
     - name: Install deps
       run: sudo apt -y install protobuf-compiler
 
+    # TODO: Use `cargo install` with a specific version during the next PolkadotSDK uplift and Rust toolchain version upgrade.
     - name: Install Tarpaulin
       run: |
         curl -L -o tarpaulin.tar.gz https://github.com/xd009642/tarpaulin/releases/download/0.31.4/cargo-tarpaulin-x86_64-unknown-linux-gnu.tar.gz