add type definitions

frontend/package.json

@@ -46,6 +46,7 @@
     "@sentry/node": "4.6.4",
     "@svgr/webpack": "^2.4.0",
     "@types/classnames": "^2.2.6",
+    "@types/compression": "^0.0.36",
     "@types/cors": "^2.8.4",
     "@types/dotenv": "^4.0.3",
     "@types/express": "^4.16.0",

frontend/yarn.lock

@@ -1771,6 +1771,12 @@
   version "2.2.6"
   resolved "https://registry.yarnpkg.com/@types/classnames/-/classnames-2.2.6.tgz#dbe8a666156d556ed018e15a4c65f08937c3f628"
 
+"@types/compression@^0.0.36":
+  version "0.0.36"
+  resolved "https://registry.yarnpkg.com/@types/compression/-/compression-0.0.36.tgz#7646602ffbfc43ea48a8bf0b2f1d5e5f9d75c0d0"
+  dependencies:
+    "@types/express" "*"
+
 "@types/connect@*":
   version "3.4.32"
   resolved "https://registry.yarnpkg.com/@types/connect/-/connect-3.4.32.tgz#aa0e9616b9435ccad02bc52b5b454ffc2c70ba28"