VED-457: fix backoff error 3

Author: Akol125

e2e/utils/immunisation_api.py

@@ -202,7 +202,8 @@ def _update_headers(self, headers=None):
         updated = {**self.headers, **{
             "X-Correlation-ID": str(uuid.uuid4()),
             "X-Request-ID": str(uuid.uuid4()),
-            "E-Tag": "1"
+            "E-Tag": "1",
+            "Accept": "application/fhir+json"
         }}
         return {**updated, **headers}