…NT_REPOS

There is a mistake in the code for SearchRepositoryCondition where it
tests topics as a string. This is incorrect for postgres where topics is
cast and stored as json. topics needs to be cast to text for this to
work. (For some reason JSON_ARRAY_LENGTH does not work, so I have taken
the simplest solution of casting to text and doing a string comparison.)

Ref go-gitea#21962 (comment)

Signed-off-by: Andrew Thornton <[email protected]>

Co-authored-by: delvh <[email protected]>