fix missing unsigned param

[hiroebe]

Fixes #2432

[kyleconroy]

@hiroebe Thanks for the fix. Could I ask you to add a new end-to-end test that includes the examples from #2432?

To do this, create a new directory inside the internal/endtoend/testdata directory named unsigned_params. In that directory copy the sqlc.json and query.sql files from the issue and generate new output using your fix.

Thanks!

[hiroebe]

@kyleconroy Thanks for the instruction. I've added a new end-to-end test.
I didn't copy the schema and queries as it is in the issue but added a smaller example. That small one should be enough to reproduce the bug being fixed, but let me know if you think the original example in the issue is more suitable.

[hiroebe]

Note: The id parameter was previously generated as int32 while it's unsigned in MySQL schema.

[kyleconroy]

Yep, this will be a breaking change, but it's necessary, as the existing code can lead to overflow errors.