Bug: changing the dependency version does not invalidate the cache

[niieani]

Reproduction

1. Install a dependency, e.g. slate@0.60.1 using your package manager
2. Run snowpack dev mode and add some example code that uses the dependency
3. Downgrade the dependency to slate@0.60.0 using your package manager
4. Re-start snowpack
5. The code still uses slate@0.60.1, even though it's no longer installed

Workaround

run rm -rf node_modules/.cache/snowpack before starting snowpack

Expected

Cache should be invalidated whenever package.json/lockfile changes, or more granularly per each package change.

[niieani]

Related to this: if you manually edit files in node_modules, snowpack will not see that change, even when restarted. Cache needs to be cleared every time.