Backporting the fix for the never type fallback change

[WaffleLapkin]

Hey! In rust-lang/rust#155499 (comment) we are experimenting with doing a change to the never type fallback, that we were planning for a while. We found that it breaks a lot crates that depend on old versions of sqlx-core and sqlx-postgres.

The newer versions already have a fix for the problem, namely 53766e4.

Would you be willing to release backports of the fix as patch versions to older versions? That would mean affected crates can fix their issues by just running cargo update. I can help with the backports, but the releases need to be done by someone with permissions to make them :)

I see that 53766e4 is quite involved, backports can probably more easily/directly fix the issue with the never type fallback.

The distribution of failures per version of

• sqlx-core is: 0.4.2 (13), 0.5.1 (5), 0.5.13 (14), 0.5.2 (2), 0.5.5 (12), 0.5.6 (1), 0.5.7 (11), 0.5.9 (2), 0.6.3 (68)
• sqlx-postgres is: 0.7.1 (1), 0.7.2 (4), 0.7.3 (48), 0.7.4 (618), 0.8.0 (40)

It would be most valuable to release backports as sqlx-postgres 0.7.x and sqlx-core 0.5.x and 0.6.x.