fix: packages/@misk/dev/package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-ASYNC-7414156

packages/@misk/dev/package.json

@@ -45,7 +45,7 @@
     "prop-types": "15.7.2",
     "sass": "1.42.1",
     "sass-loader": "8.0.2",
-    "source-map-loader": "0.2.4",
+    "source-map-loader": "1.0.0",
     "style-loader": "1.2.1",
     "ts-loader": "7.0.5",
     "tslib": "2.3.1",
@@ -54,7 +54,7 @@
     "webpack": "4.43.0",
     "webpack-bundle-analyzer": "3.7.0",
     "webpack-cli": "3.3.11",
-    "webpack-dev-server": "4.3.1",
+    "webpack-dev-server": "4.9.0",
     "webpack-merge": "4.2.2"
   },
   "devDependencies": {