Do not enable sparse registry on stable

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.3.7] - 2023-01-31
+
+### Fixed
+
+* Disable the stable access to the sparse registry.
+    Setting the value causes problem on version before stabilization, e.g., 1.67.
+    For example, "cargo add" fails.
+
 ## [1.3.6] - 2023-01-31
 
 ### Fixed

action.yml

@@ -63,11 +63,13 @@ runs:
         echo "RUST_BACKTRACE=short" >> $GITHUB_ENV
         echo "RUSTFLAGS=-D warnings" >> $GITHUB_ENV
         # Enable faster sparse index on nightly
+        # The value is ignored on stable and causes no problems
         # https://internals.rust-lang.org/t/call-for-testing-cargo-sparse-registry/16862
         echo "CARGO_UNSTABLE_SPARSE_REGISTRY=true" >> $GITHUB_ENV
         # Enable sparse index after stabilization
+        # This causes warnings on stable 1.67, e.g., when using "cargo add"
         # https://github.com/rust-lang/cargo/pull/11224
-        echo "CARGO_REGISTRIES_CRATES_IO_PROTOCOL=sparse" >> $GITHUB_ENV
+        # echo "CARGO_REGISTRIES_CRATES_IO_PROTOCOL=sparse" >> $GITHUB_ENV
       shell: bash
     - name: "Install Rust Problem Matcher"
       run: echo "::add-matcher::${{ github.action_path }}/rust.json"