Python: Make all PEP249 implementations private

Since we're still sticking with `private by default` at least for a while longer.

Author: RasmusWL

python/ql/src/semmle/python/frameworks/MySQLdb.qll

@@ -17,7 +17,7 @@ private import PEP249
  * - https://mysqlclient.readthedocs.io/index.html
  * - https://pypi.org/project/MySQL-python/
  */
-module MySQLdb {
+private module MySQLdb {
   // ---------------------------------------------------------------------------
   // MySQLdb
   // ---------------------------------------------------------------------------

python/ql/src/semmle/python/frameworks/MysqlConnectorPython.qll

@@ -17,7 +17,7 @@ private import PEP249
  * - https://dev.mysql.com/doc/connector-python/en/
  * - https://dev.mysql.com/doc/connector-python/en/connector-python-example-connecting.html
  */
-module MysqlConnectorPython {
+private module MysqlConnectorPython {
   // ---------------------------------------------------------------------------
   // mysql
   // ---------------------------------------------------------------------------

python/ql/src/semmle/python/frameworks/Psycopg2.qll

@@ -17,7 +17,7 @@ private import PEP249
  * - https://www.psycopg.org/docs/
  * - https://pypi.org/project/psycopg2/
  */
-module Psycopg2 {
+private module Psycopg2 {
   // ---------------------------------------------------------------------------
   // Psycopg
   // ---------------------------------------------------------------------------