fix: INCONSISTENT_IMPORT_ASSERTIONS warning

Rollup v3 has introduced some support of import assertions in
rollup/rollup#4646. In particular, it uses
an `{ assertions: { type: <xxx> } }` object to track the assertions
linked to a module. However, this does not seem to be set in preload,
whereas it _is_ set afterwards. This results in a warning.

In order to silence the warning, we need to explicitly tell rollup
about the assertions type, so that this piece of information is
available even at preload time.

Note: this also makes the test 'handles garbage' pass. Without this
rollup issues 2 warnings instead of 1 expected (resulting in test failure).

src/index.js

@@ -140,7 +140,9 @@ export default sheet;`;
           // case where the module has not been loaded yet.
           if (!moduleInfo) {
             self
-              .load({ id: resolvedId.id, meta })
+              // {meta} is used by this plugin to track the assertion type
+              // {assertions} is used by rollup v3 for the same purpose
+              .load({ id: resolvedId.id, meta, assertions: { type } })
               // errors parsing the file are already captured, so don't repeat error
               // https://github.com/rollup/rollup/blob/275dc2fa34e1aaad37a29360570dc85b1ba019a6/src/Module.ts#L837
               // Question: could it be though that load() rejects for an error type