Allow specifying stdin (#360)

* Allow specifying stdin

packages/exec/src/toolrunner.ts

@@ -524,6 +524,14 @@ export class ToolRunner extends events.EventEmitter {
           resolve(exitCode)
         }
       })
+
+      if (this.options.input) {
+        if (!cp.stdin) {
+          throw new Error('child process missing stdin')
+        }
+
+        cp.stdin.end(this.options.input)
+      }
     })
   }
 }