CustomType tests occasionally fail with CannotResolveType

[jayvdb]

e.g. https://github.com/Electron100/butane/actions/runs/8320323805/job/22764866696

---- auto_pk_sqlite stdout ----
thread 'auto_pk_sqlite' panicked at butane_test_helper\src\lib.rs:194:59:
called `Result::unwrap()` on an `Err` value: CannotResolveType("CustomType(Frobnozzle)")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
...

https://github.com/Electron100/butane/actions/runs/8199686014/job/22425171195

---- basic_committed_transaction_sqlite stdout ----
connecting to :memory:
FsMigration { fs: OsFilesystem, root: "/home/runner/work/butane/butane/butane/.butane/migrations/current" }
error: test failed, to rerun pass `--test basic`
thread 'basic_committed_transaction_sqlite' panicked at butane_test_helper/src/lib.rs:186:59:
called `Result::unwrap()` on an `Err` value: CannotResolveType("CustomType(Point)")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

I have also seen the problem locally a few times.

It appears to always happen when running basic.rs tests.