[COMPLIANCE] Add Copyright and License Headers (#8)

Co-authored-by: hashicorp-copywrite[bot] <110428419+hashicorp-copywrite[bot]@users.noreply.github.com>

Author: hashicorp-copywrite[bot]

index.ts

@@ -1,3 +1,8 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 import * as core from "@actions/core";
 import { setupBinary } from "./setup-binary";
 

setup-binary.ts

@@ -1,3 +1,8 @@
+/**
+ * Copyright (c) HashiCorp, Inc.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
 import * as core from "@actions/core";
 import * as hc from "@hashicorp/js-releases";
 import * as io from "@actions/io";