Full release of actions/core 1.6.0 with oidc behavior (#919)

* OIDC Client for actions/core

Co-authored-by: Sourav Chanduka <souravchanduka37@gmail.com>
Co-authored-by: Sourav Chanduka <souravchanduka@users.noreply.github.com>
Co-authored-by: Tingluo Huang <tingluohuang@github.com>

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@actions/core",
-  "version": "1.5.0",
+  "version": "1.6.0",
   "description": "Actions core lib",
   "keywords": [
     "github",
@@ -35,6 +35,9 @@
   "bugs": {
     "url": "https://github.com/actions/toolkit/issues"
   },
+  "dependencies": {
+    "@actions/http-client": "^1.0.11"
+  },
   "devDependencies": {
     "@types/node": "^12.0.2"
   }