pgsql: PL/Python: Fix tests for older Python versions

PL/Python: Fix tests for older Python versions

Commit 8561e4840c81f7e345be2df170839846814fa004 neglected to handle
older Python versions that don't support the "with" statement.  So write
the tests in a way that older versions can handle as well.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/f498704346a4ce4953fc5f837cacb545b3166ee1

Modified Files
--------------
src/pl/plpython/expected/plpython_transaction.out | 5 +++--
src/pl/plpython/sql/plpython_transaction.sql      | 5 +++--
2 files changed, 6 insertions(+), 4 deletions(-)