Use the correct variable to enable sparse registry access

https://github.com/rust-lang/cargo/pull/11224
https://github.com/dtolnay/rust-toolchain/pull/54

CHANGELOG.md

@@ -7,6 +7,21 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [1.3.6] - 2023-01-31
+
+### Fixed
+
+* The the correct environment variable to enable the sparse registry access.
+    The pull request originally had the wrong value, without `CARGO_` prefix.
+
+## [1.3.5] - 2023-01-21
+
+### Changed
+
+* Use the newly stabilized setting to enable sparse registry access.
+    This speeds up access to the crate registry and is in addition to the unstable nightly env var.
+    <https://github.com/rust-lang/cargo/pull/11224>
+
 ## [1.3.4] - 2022-10-15
 
 ### Changed

action.yml

@@ -65,6 +65,9 @@ runs:
         # Enable faster sparse index on nightly
         # 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
+        # https://github.com/rust-lang/cargo/pull/11224
+        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"