fix: bug in test_retries_on_cae_failure test

There is a bug in the assertion of the test_retries_on_cae_failure test
in http/httpx/tests/test_httpx_request_adapter.py. The mock claim
entered in mock_cae_failure_response in http/httpx/tests/conftest.py
ends with a "=". It is unclear how this test ever passed previously!

packages/http/httpx/tests/test_httpx_request_adapter.py

@@ -394,7 +394,7 @@ async def test_retries_on_cae_failure(
             {
                 "claims": (
                     "eyJhY2Nlc3NfdG9rZW4iOnsibmJmIjp7ImVzc2VudGlhbCI6dHJ1ZSwgInZhbH"
-                    "VlIjoiMTYwNDEwNjY1MSJ9fX0"
+                    "VlIjoiMTYwNDEwNjY1MSJ9fX0="
                 )
             },
         ),