Fix Data Type

This was the wrong type being returned by the API. The spec is now corrected.

Signed-off-by: Elliot Huffman <elliot_huffman@shilab.com>

Author: elliot-huffman

specs/SHIELD.json

@@ -1123,7 +1123,7 @@
                 "responses": {
                     "200": {
                         "content": {
-                            "application/json": {
+                            "text/plain": {
                                 "schema": {
                                     "description": "Access token that SHIELD uses to prove it is a valid recipient of credentials.",
                                     "type": "string",