Do not externalise inertia helpers

Due to a [bugfix](vitejs/vite#9146) in version
Vite 3.0.1 we now need to revert to referencing the package by name
directly in order to have Vite not externalise the helpers.

Fixes: #93

Author: timacdonald

src/index.ts

@@ -360,7 +360,7 @@ function noExternalInertiaHelpers(config: UserConfig): true|Array<string|RegExp>
     /* eslint-disable-next-line @typescript-eslint/ban-ts-comment */
     /* @ts-ignore */
     const userNoExternal = (config.ssr as SSROptions|undefined)?.noExternal
-    const pluginNoExternal = ['laravel-vite-plugin/inertia-helpers']
+    const pluginNoExternal = ['laravel-vite-plugin']
 
     if (userNoExternal === true) {
         return true