fix: upgrade gulp-sass from 4.1.0 to 4.1.1

Snyk has created this PR to upgrade gulp-sass from 4.1.0 to 4.1.1.

See this package in npm:
gulp-sass

See this project in Snyk:
https://app.snyk.io/org/gsa-pages/project/62dba7a2-222e-47c4-b000-ec3233b593e2?utm_source=github&utm_medium=referral&page=upgrade-pr

Author: snyk-bot

package-lock.json

@@ -5,7 +5,7 @@
   },
   "dependencies": {
     "gulp": "^4.0.2",
-    "gulp-sass": "^4.1.0",
+    "gulp-sass": "^4.1.1",
     "gulp-sourcemaps": "^3.0.0",
     "uswds": "^1.3.0"
   }