lower httpx

setup.cfg

@@ -55,7 +55,7 @@ dev =
     pyfakefs>=4.5.3
     pytest==7.2.0
     pytest-cov==3.0.0
-    pytest-httpx==0.29.*
+    pytest-httpx==0.28.*
     pytest-mock==3.6.1
     pytest-timeout==2.1.0
     pytest-trio==0.8.0