Bump gulp-autoprefixer from 3.1.0 to 7.0.1

Bumps [gulp-autoprefixer](https://github.com/sindresorhus/gulp-autoprefixer) from 3.1.0 to 7.0.1.
- [Release notes](https://github.com/sindresorhus/gulp-autoprefixer/releases)
- [Commits](sindresorhus/gulp-autoprefixer@v3.1.0...v7.0.1)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

Diff for: package.json

@@ -56,7 +56,7 @@
     "exports-loader": "^0.6.3",
     "expose-loader": "^0.7.1",
     "gulp": "3.9.1",
-    "gulp-autoprefixer": "3.1.0",
+    "gulp-autoprefixer": "7.0.1",
     "gulp-changed": "1.3.0",
     "gulp-csscomb": "^3.0.7",
     "gulp-cssnano": "2.1.2",