Fix SCSS error and frontend linter

Last commit bumped the javascript SCSS dependency and now //deep is
not allowed in SCSS anymore. The recommended way is the ::v-deep
pseudo-element.

The change in the vue component fixes the issue, but the linter
complains. So we need to change the linter rule as well.

https://phabricator.endlessm.com/T31931

Author: manuq

.stylelintrc.js

@@ -1 +1,9 @@
-module.exports = require('kolibri-tools/.stylelintrc');
+const Config = require('kolibri-tools/.stylelintrc');
+Config.rules['selector-pseudo-element-no-unknown'] = [
+  true,
+  {
+    ignorePseudoElements: ['v-deep'],
+  },
+];
+
+module.exports = Config;

kolibri_explore_plugin/assets/src/views/ChannelCard.vue

@@ -164,7 +164,7 @@
     right: $margin;
   }
 
-  /deep/.card-thumbnail-wrapper {
+  ::v-deep.card-thumbnail-wrapper {
     max-width: 100%;
   }