revert imagemin-svgo to 9.0.0

[lizthegrey]

Until webpack-contrib/image-minimizer-webpack-plugin#237 is solved, we need to roll back imagemin-svgo

Solves these errors that have cropped up the past 2 weeks:

WARNING in ./src/client/shared/res/LoadingSpinner-spinner.svg
Module Warning (from ./node_modules/image-minimizer-webpack-plugin/dist/loader.js):
Unknown plugin: imagemin-svgo

Did you forget to install the plugin?
You can install it with:

$ npm install imagemin-svgo --save-dev
$ yarn add imagemin-svgo --dev
 @ ./node_modules/vue-loader/dist/templateLoader.js??ruleSet[1].rules[1]!./node_modules/vue-loader/dist/index.js??ruleSet[1].rules[7].use[0]!./src/client/shared/LoadingSpinner.vue?vue&type=template&id=440c8cdd&scoped=true 2:0-57 27:21-31
 @ ./src/client/shared/LoadingSpinner.vue?vue&type=template&id=440c8cdd&scoped=true 1:0-232 1:0-232
 @ ./src/client/shared/LoadingSpinner.vue 1:0-87 6:16-22
 @ ./node_modules/ts-loader/index.js??clonedRuleSet-1!./node_modules/vue-loader/dist/index.js??ruleSet[1].rules[7].use[0]!./src/client/admin/AccountLog.vue?vue&type=script&lang=ts
 @ ./src/client/admin/AccountLog.vue?vue&type=script&lang=ts 1:0-202 1:0-202 1:203-394 1:203-394
 @ ./src/client/admin/AccountLog.vue 2:0-61 3:0-56 3:0-56 6:0-13 7:0-16 9:15-21
 @ ./src/client/home.ts