remove legacy polyfills and unused dependencies

package.json

@@ -55,7 +55,6 @@
   "dependencies": {
     "@babel/runtime": "^7.12.5",
     "await-lock": "^2.1.0",
-    "blueimp-canvas-to-blob": "^3.28.0",
     "browser-encrypt-attachment": "^0.3.0",
     "browser-request": "^0.3.3",
     "cheerio": "^1.0.0-rc.9",
@@ -88,7 +87,6 @@
     "png-chunks-extract": "^1.0.0",
     "prop-types": "^15.7.2",
     "qrcode": "^1.4.4",
-    "qs": "^6.9.6",
     "re-resizable": "^6.9.0",
     "react": "^17.0.2",
     "react-beautiful-dnd": "^4.0.1",
@@ -99,7 +97,6 @@
     "rfc4648": "^1.4.0",
     "sanitize-html": "^2.3.2",
     "tar-js": "^0.3.0",
-    "text-encoding-utf-8": "^1.0.2",
     "url": "^0.11.0",
     "what-input": "^5.2.10",
     "zxcvbn": "^4.4.2"