Improve `test_sqlite3.test_sqlite_row_iter`

[sobolevn]

While working on #100457 I've noticed that test_sqlite_row_iter can be improved. Right now it is defined as:

    def test_sqlite_row_iter(self):
        """Checks if the row object is iterable"""
        self.con.row_factory = sqlite.Row
        row = self.con.execute("select 1 as a, 2 as b").fetchone()
        for col in row:
           pass

Well, there are several issues:

1. We do not check what values it actually returns
2. We do not check whether or not it is iterable the second time, because some types are implemented as generators and cannot be iterated over the second time

I will send a PR with the improved test.

Linked PRs

• gh-100553: Improve accuracy of sqlite3.Row iter test #100555
• [3.11] gh-100553: Improve accuracy of sqlite3.Row iter test (GH-100555) #100564
• [3.10] gh-100553: Improve accuracy of sqlite3.Row iter test (GH-100555) #100565

[pochmann]

Also, col and items are misleading names, better use value and values (that's what the Row documentation calls them).

[erlend-aasland]

Thanks, Nikita, good catch!