Update dependency autoprefixer to v9.7.2 (woocommerce#3280)

Author: renovate[bot]

package-lock.json

@@ -124,7 +124,7 @@
  "@wordpress/jest-preset-default": "5.1.1",
  "@wordpress/postcss-themes": "1.0.5",
  "ast-types": "0.13.2",
- "autoprefixer": "9.7.1",
+ "autoprefixer": "9.7.2",
  "babel-core": "7.0.0-bridge.0",
  "babel-eslint": "10.0.3",
  "babel-loader": "8.0.6",