add qs package

packages/slack/package.json

@@ -19,6 +19,7 @@
     "bunyan": "^1.8.15",
     "extensible-custom-error": "^0.0.7",
     "http-errors": "^1.8.0",
+    "qs": "^6.10.2",
     "universal-bunyan": "^0.9.2",
     "url-join": "^4.0.0"
   },

yarn.lock

@@ -16690,6 +16690,13 @@ qs@6.7.0:
   resolved "https://registry.yarnpkg.com/qs/-/qs-6.7.0.tgz#41dc1a015e3d581f1621776be31afb2876a9b1bc"
   integrity sha512-VCdBRNFTX1fyE7Nb6FYoURo/SPe62QCaAyzJvUjwRaIsc+NePBEniHlvxFmmX56+HZphIGtV0XeCirBtpDrTyQ==
 
+qs@^6.10.2:
+  version "6.10.2"
+  resolved "https://registry.yarnpkg.com/qs/-/qs-6.10.2.tgz#c1431bea37fc5b24c5bdbafa20f16bdf2a4b9ffe"
+  integrity sha512-mSIdjzqznWgfd4pMii7sHtaYF8rx8861hBO80SraY5GT0XQibWZWJSid0avzHGkDIZLImux2S5mXO0Hfct2QCw==
+  dependencies:
+    side-channel "^1.0.4"
+
 qs@^6.9.4:
   version "6.10.1"
   resolved "https://registry.yarnpkg.com/qs/-/qs-6.10.1.tgz#4931482fa8d647a5aab799c5271d2133b981fb6a"