ci: Fix getting `cache` value from inputs (#3364)

.github/workflows/reusable-tests.yaml

@@ -19,7 +19,7 @@ on:
         required: true
         type: string
 env:
-  CACHE: inputs.cache
+  CACHE: ${{ inputs.cache }}
   SOLANA_CLI_VERSION: ${{ inputs.solana_cli_version }}
   NODE_VERSION: ${{ inputs.node_version }}
   CARGO_PROFILE: ${{ inputs.cargo_profile }}