chore: fix Storybook and Babel config (#610)

Author: arthurdenner

.storybook/main.js

@@ -1,4 +1,8 @@
 module.exports = {
   stories: ['../stories/**/*.stories.tsx'],
   addons: ['@storybook/addon-knobs', '@storybook/addon-storysource'],
+  babel: async options => ({
+    ...options,
+    plugins: options.plugins.concat('@babel/plugin-proposal-class-properties'),
+  }),
 };

package.json

@@ -41,10 +41,11 @@
   },
   "devDependencies": {
     "@babel/core": "7.13.10",
-    "@storybook/addon-knobs": "6.2.9",
-    "@storybook/addon-storysource": "6.2.9",
-    "@storybook/addons": "6.2.9",
-    "@storybook/react": "6.2.9",
+    "@babel/plugin-proposal-class-properties": "7.13.0",
+    "@storybook/addon-knobs": "6.3.0",
+    "@storybook/addon-storysource": "6.3.1",
+    "@storybook/addons": "6.3.1",
+    "@storybook/react": "6.3.1",
     "@testing-library/jest-dom": "5.12.0",
     "@testing-library/react": "11.2.7",
     "@testing-library/user-event": "13.1.9",
@@ -77,6 +78,7 @@
     "semantic-ui-react": ">=0.75.0"
   },
   "resolutions": {
+    "@babel/plugin-proposal-class-properties": "7.13.0",
     "handlebars": "4.5.0"
   },
   "jest": {