Handle webpack .svg assets in line with .pngs

govuk-frontend 5.7 replaces the existing 'govuk-crest.png' file with
'govuk-crest.svg'. This causes the build to fail due to the way webpack
handles .svg files. This commit fixes this by bringing handling of .svg
files in line with the approach currently used for .pngs.

config/webpack/webpack.config.js

@@ -61,15 +61,15 @@ module.exports = {
         ]
       },
       {
-        test: /\.(png)$/i,
+        test: /\.(png|svg)$/i,
         type: 'asset/resource'
       },
       {
         test: /\.(woff|woff2|ttf)$/i,
         type: 'asset/resource'
       },
       {
-        test: /\.(svg|ico)$/,
+        test: /\.(ico)$/,
         loader: 'file-loader',
         options: {
           name: '[name].[ext]'