chore: remove unreachable branch

Author: haoqunjiang

lib/plugin-webpack4.js

@@ -10,13 +10,7 @@ class VueLoaderPlugin {
     if (compiler.hooks) {
       // webpack 4
       compiler.hooks.compilation.tap(id, compilation => {
-        let normalModuleLoader
-        if (Object.isFrozen(compilation.hooks)) {
-          // webpack 5
-          normalModuleLoader = require('webpack/lib/NormalModule').getCompilationHooks(compilation).loader
-        } else {
-          normalModuleLoader = compilation.hooks.normalModuleLoader
-        }
+        const normalModuleLoader = compilation.hooks.normalModuleLoader
         normalModuleLoader.tap(id, loaderContext => {
           loaderContext[NS] = true
         })