pgsql: Set client encoding explicitly in plpython_unicode test

Set client encoding explicitly in plpython_unicode test

This will (hopefully) eliminate the need for the
plpython_unicode_0.out expected file.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/5809a6458450a59f8c4a7a25beaefc81cff563d1

Modified Files
--------------
src/pl/plpython/expected/README | 3 +-
src/pl/plpython/expected/plpython_unicode.out | 1 +
src/pl/plpython/expected/plpython_unicode_0.out | 50 -----------------------
src/pl/plpython/expected/plpython_unicode_3.out | 1 +
src/pl/plpython/sql/plpython_unicode.sql | 2 +
5 files changed, 5 insertions(+), 52 deletions(-)