fix(deps): update dependency postcss-simple-vars to v7

Author: renovate[bot]

package-lock.json

@@ -76,7 +76,7 @@
     "papaparse": "5.4.1",
     "postcss-import": "12.0.1",
     "postcss-loader": "4.3.0",
-    "postcss-simple-vars": "5.0.2",
+    "postcss-simple-vars": "7.0.1",
     "prop-types": "15.8.1",
     "query-string": "5.1.1",
     "raw-loader": "4.0.2",