pg-schema testsuite needs a running server (#8077)

Author: juhp

build-constraints.yaml

@@ -8274,6 +8274,7 @@ expected-test-failures:
     - persistent-redis # redis - https://github.com/fpco/stackage/pull/1581
     - pinecone # Requires pinecone API key
     - pipes-mongodb
+    - pg-schema # needs a running server socket
     - postgresql-libpq-notify
     - postgresql-query # PostgreSQL
     - postgresql-simple # PostgreSQL