Resolve @svgr/webpack relative to next-svgr

[elliottsj]

Previously, webpack would attempt to resolve @svgr/webpack relative to the Next.js project, which would result in an error like this using strict package managers like pnpm / Yarn PnP:

Module not found: Can't resolve '@svgr/webpack' in '/path/to/project'

Using require.resolve() fixes this.