esbuild 0.16.1

This is a hotfix for the previous release.

Re-allow importing JSON with the copy loader using an import assertion

The previous release made it so when assert { type: 'json' } is present on an import statement, esbuild validated that the json loader was used. This is what an import assertion is supposed to do. However, I forgot about the relatively new copy loader, which sort of behaves as if the import path was marked as external (and thus not loaded at all) except that the file is copied to the output directory and the import path is rewritten to point to the copy. In this case whatever JavaScript runtime ends up running the code is the one to evaluate the import assertion. So esbuild should really allow this case as well. With this release, esbuild now allows both the json and copy loaders when an assert { type: 'json' } import assertion is present.