Update various 3rd party dependencies

package.json

@@ -60,7 +60,7 @@
     "@babel/plugin-proposal-nullish-coalescing-operator": "^7.8.3",
     "@babel/plugin-proposal-optional-chaining": "^7.9.0",
     "@babel/plugin-syntax-dynamic-import": "^7.2.0",
-    "@babel/preset-env": "^7.5.4",
+    "@babel/preset-env": "^7.9.0",
     "@converse/headless": "file:src/headless",
     "@fortawesome/fontawesome-free": "5.13.0",
     "@lit-element-bootstrap/button": "^1.0.0",
@@ -75,8 +75,8 @@
     "bootstrap.native-loader": "2.0.0",
     "clean-css-cli": "^4.3.0",
     "clean-webpack-plugin": "^3.0.0",
-    "copy-webpack-plugin": "^5.0.4",
-    "css-loader": "^3.0.0",
+    "copy-webpack-plugin": "^5.1.1",
+    "css-loader": "^3.5.0",
     "dayjs": "^1.8.15",
     "eslint": "^6.3.0",
     "eslint-plugin-lodash": "^5.1.0",
@@ -91,17 +91,17 @@
     "jasmine-core": "2.99.1",
     "jsdoc": "^3.6.2",
     "lerna": "^3.20.2",
-    "lit-html": "^1.1.2",
+    "lit-html": "^1.2.1",
     "lodash-template-webpack-loader": "jcbrand/lodash-template-webpack-loader",
     "mini-css-extract-plugin": "^0.9.0",
-    "minimist": "^1.2.0",
-    "node-sass": "^4.12.0",
+    "minimist": "^1.2.3",
+    "node-sass": "^4.13.1",
     "npm": "^6.11.3",
     "po-loader": "^0.5.0",
-    "po2json": "^1.0.0-alpha",
+    "po2json": "^1.0.0-beta",
     "postcss-clean": "^1.1.0",
     "postcss-loader": "^3.0.0",
-    "prettierx": "^0.6.0",
+    "prettierx": "^0.11.0",
     "requirejs": "2.3.6",
     "run-headless-chromium": "^0.1.1",
     "sass-loader": "^7.1.0",
@@ -111,8 +111,8 @@
     "uglify-es": "^3.3.9",
     "uglify-js": "^3.7.4",
     "urijs": "^1.19.1",
-    "webpack": "^4.35.3",
-    "webpack-cli": "^3.3.5",
+    "webpack": "^4.42.1",
+    "webpack-cli": "^3.3.11",
     "webpack-dev-server": "^3.8.0",
     "webpack-merge": "^4.2.1",
     "xss": "^1.0.6"