pgsql: Fix memory leak in PLySequence_ToJsonbValue()

Fix memory leak in PLySequence_ToJsonbValue()

PyObject returned from PySequence_GetItem() is not released.  Similar code in PLyMapping_ToJsonbValue() is correct,
becauseaccording to Python documentation 
PyList_GetItem() and PyTuple_GetItem() return a borrowed reference while
PySequence_GetItem() returns new reference.  contrib/jsonb_plpython is new
in PostgreSQL 11, no backpatch is needed.

Author: Nikita Glukhov
Discussion: https://postgr.es/m/6001af16-b242-2527-bc7e-84b8a959163b%40postgrespro.ru

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/dad8bed04ab98ada84ecd58ace6f59839aa161c4

Modified Files
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contrib/jsonb_plpython/jsonb_plpython.c | 2 ++
1 file changed, 2 insertions(+)