chore: Update dependencies.properties to use gax's version

Author: lqiu96

gax-java/dependencies.properties

@@ -16,8 +16,8 @@ version.gax_grpc=2.30.0
 # {x-version-update-start:gax:current}
 version.gax_bom=2.30.0
 # {x-version-update-end}
-# {x-version-update-start:gax-httpjson:current}
-version.gax_httpjson=0.115.0
+# {x-version-update-start:gax:current}
+version.gax_httpjson=2.30.0
 # {x-version-update-end}
 
 # Versions for dependencies which actual artifacts differ between Bazel and Gradle.