HTTP errors when the token is undefined

[peter-murray]

Description:
When the token is undefined (as the use of the action is not on dotcom), the http library is generating an error as the authorization header is set to undefined.

This change only populates the authorization header if there is a value present which makes this action work correctly for Microsoft variants of Java when not on dotcom.

Check list:

• Mark if documentation changes are required.
• Mark if tests were added or updated to cover the changes.