build(deps): bump openpolicyagent/opa from 0.67.0-istio to 0.68.0-istio in /examples/ext_authz in the examples-ext-authz group across 1 directory

build(deps): bump openpolicyagent/opa from 0.67.0-istio to 0.68.0-istio in /examples/ext_authz in the examples-ext-authz group across 1 directory #1216