During Gabbi tests server returns one of
application/json
application/json; charset=UTF-8
in a Content-Type HTTP header, depending on which test is being run.
This might be related to different pip/pip3 versions and dependencies
installed being used during standalone vs. containerized tests.
This patch allows for both returned header's values to be accepted as
valid as a remediate solution until versions of packages and pip/pip3
usage is unified.
Change-Id: Ifb8f2d68e3474946b3df154cb016cc18cfc95d23
5241d1d6ea