Resolved issue with https://dcloud-dna-center-inst-rtp.cisco.com

[tylerxc0m]

Hey Knox,

Here is my attempt to fix an issue with the code from the Cisco CCNP Automating Enterprise Solutions (300-435 ENAUTO) - 88. Getting Authenticated video. Guessing Cisco has updated the https://dcloud-dna-center-inst-rtp.cisco.com instance and inadvertently broke the code.

Changes are to use https://sandboxdnac.cisco.com always-on-instance and to use an authorization header base64 encoded as per Cisco guidelines.

Hope this code contribute helps out the rest of the Cisco learning community.

Kind regards Tyler