fix(test): use single-quotes for strings in sql statements

Currently, in the sharness test suites, we use double-quotes for string literals in SQL statements passed to sqlite3.

With sqlite version 3.41, the usage of double-quotes for string literals is deactivated by default:
We'll need to switch to single-quotes in our tests.

See section 6.f. at https://www.sqlite.org/releaselog/3_41_0.html

Failing tests with sqlite 3.41: https://gitlab.archlinux.org/moson/aurweb/-/jobs/129032

Signed-off-by: moson-mo mo-son@mailbox.org