bitbake: persist_data: close connection in SQLTable __exit__

A Connection's __exit__ does not close the connection, but rather deals
with transactions. See https://docs.python.org/3/library/sqlite3.html#how-to-use-the-connection-context-manager

This change is not necessary on 'master' because persist_data was
removed.

(Bitbake rev: c9ea354c2df3d94b9ebe7810e83df9efb6007013)

Signed-off-by: Chris Laplante <chris.laplante@agilent.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
Signed-off-by: Steve Sakoman <steve@sakoman.com>

bitbake/lib/bb/persist_data.py

@@ -154,6 +154,7 @@ class SQLTable(collections.abc.MutableMapping):
 
     def __exit__(self, *excinfo):
         self.connection.__exit__(*excinfo)
+        self.connection.close()
 
     @_Decorators.retry()
     @_Decorators.transaction