pgsql: Fix path delimiters in connection string on Windows

Fix path delimiters in connection string on Windows

The temporary path generated in commit c113d8ad5 cannot be passed as-is in
the connection string on Windows since the path delimiting backslashes will
be treated as escape characters. Fix by converting backslash to slash as in
similar path usecases in other tests.

Reported-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20211202195130.e7pprpsx4ell22sp@alap3.anarazel.de

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/49422ad0cc88c91a38522b2a7b222c2f2c939f82

Modified Files
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src/test/ssl/t/001_ssltests.pl | 3 ++-
src/test/ssl/t/002_scram.pl    | 1 +
src/test/ssl/t/003_sslinfo.pl  | 1 +
3 files changed, 4 insertions(+), 1 deletion(-)