pgsql: Fix typo in create_index.sql.

Fix typo in create_index.sql.

Introduced by 578b229718e.

Author: Dean Rasheed <dean.a.rasheed@gmail.com>
Reviewed-by: Tender Wang <tndrwang@gmail.com>
Discussion: https://postgr.es/m/CAEZATCV_CzRSOPMf1gbHQ7xTmyrV6kE7ViCBD6B81WF7GfTAEA@mail.gmail.com
Backpatch-through: 13

Branch
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REL_14_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/0c27d80d5f0f877a8eec333626348f947f4b6597

Modified Files
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src/test/regress/expected/create_index.out | 4 ++--
src/test/regress/sql/create_index.sql      | 2 +-
2 files changed, 3 insertions(+), 3 deletions(-)