pq tests moved into a dir of its own

diff --git a/tests/test_pq_conninfo.py b/tests/pq/test_conninfo.py
similarity index 100%
rename from tests/test_pq_conninfo.py
rename to tests/pq/test_conninfo.py

diff --git a/tests/test_pq_exec.py b/tests/pq/test_exec.py
similarity index 100%
rename from tests/test_pq_exec.py
rename to tests/pq/test_exec.py

diff --git a/tests/test_pq_pgconn.py b/tests/pq/test_pgconn.py
similarity index 100%
rename from tests/test_pq_pgconn.py
rename to tests/pq/test_pgconn.py