Use kind-of >=6.0.3 everywhere (#165)

* Use kind-of >=6.0.3 everywhere

This repo's dependencies currently use [older versions](https://github.com/paritytech/operationsproxy/blob/1e42f36ab60f6368f673211d53e9b887227dc11d/yarn.lock#L3521) of kind-of which have a possibly exploitable vulnerability ([original issue](jonschlinkert/kind-of#30), [PR](jonschlinkert/kind-of#31)).

* Update yarn.lock

package.json

@@ -22,6 +22,9 @@
     "webpack-cli": "3.3.10",
     "webpack-dev-server": "3.10.1"
   },
+  "resolutions": {
+    "kind-of": ">=6.0.3"
+  },
   "scripts": {
     "test": "echo \"Error: no test specified\" && exit 1",
     "lint": "semistandard",

yarn.lock

@@ -3237,11 +3237,6 @@ is-binary-path@^1.0.0:
   dependencies:
     binary-extensions "^1.0.0"
 
-is-buffer@^1.1.5:
-  version "1.1.6"
-  resolved "https://registry.yarnpkg.com/is-buffer/-/is-buffer-1.1.6.tgz#efaa2ea9daa0d7ab2ea13a97b2b8ad51fefbe8be"
-  integrity sha512-NcdALwpXkTm5Zvvbk7owOUSvVvBKDgKP5/ewfXEznmQFfs4ZRmanOeKBTjRVjka3QFoN6XJ+9F3USqfHqTaU5w==
-
 is-callable@^1.1.4:
   version "1.1.4"
   resolved "https://registry.yarnpkg.com/is-callable/-/is-callable-1.1.4.tgz#1e1adf219e1eeb684d691f9d6a05ff0d30a24d75"
@@ -3518,29 +3513,10 @@ killable@^1.0.1:
   resolved "https://registry.yarnpkg.com/killable/-/killable-1.0.1.tgz#4c8ce441187a061c7474fb87ca08e2a638194892"
   integrity sha512-LzqtLKlUwirEUyl/nicirVmNiPvYs7l5n8wOPP7fyJVpUPkvCnW/vuiXGpylGUlnPDnB7311rARzAt3Mhswpjg==
 
-kind-of@^3.0.2, kind-of@^3.0.3, kind-of@^3.2.0:
-  version "3.2.2"
-  resolved "https://registry.yarnpkg.com/kind-of/-/kind-of-3.2.2.tgz#31ea21a734bab9bbb0f32466d893aea51e4a3c64"
-  integrity sha1-MeohpzS6ubuw8yRm2JOupR5KPGQ=
-  dependencies:
-    is-buffer "^1.1.5"
-
-kind-of@^4.0.0:
-  version "4.0.0"
-  resolved "https://registry.yarnpkg.com/kind-of/-/kind-of-4.0.0.tgz#20813df3d712928b207378691a45066fae72dd57"
-  integrity sha1-IIE989cSkosgc3hpGkUGb65y3Vc=
-  dependencies:
-    is-buffer "^1.1.5"
-
-kind-of@^5.0.0:
-  version "5.1.0"
-  resolved "https://registry.yarnpkg.com/kind-of/-/kind-of-5.1.0.tgz#729c91e2d857b7a419a1f9aa65685c4c33f5845d"
-  integrity sha512-NGEErnH6F2vUuXDh+OlbcKW7/wOcfdRHaZ7VWtqCztfHri/++YKmP51OdWeGPuqCOba6kk2OTe5d02VmTB80Pw==
-
-kind-of@^6.0.0, kind-of@^6.0.2:
-  version "6.0.2"
-  resolved "https://registry.yarnpkg.com/kind-of/-/kind-of-6.0.2.tgz#01146b36a6218e64e58f3a8d66de5d7fc6f6d051"
-  integrity sha512-s5kLOcnH0XqDO+FvuaLX8DDjZ18CGFk7VygH40QoKPUQhW4e2rvM0rwUq0t8IQDOwYSeLK01U90OjzBTme2QqA==
+kind-of@>=6.0.3, kind-of@^3.0.2, kind-of@^3.0.3, kind-of@^3.2.0, kind-of@^4.0.0, kind-of@^5.0.0, kind-of@^6.0.0, kind-of@^6.0.2:
+  version "6.0.3"
+  resolved "https://registry.yarnpkg.com/kind-of/-/kind-of-6.0.3.tgz#07c05034a6c349fa06e24fa35aa76db4580ce4dd"
+  integrity sha512-dcS1ul+9tmeD95T+x28/ehLgd9mENa3LsvDTtzm3vyBEO7RPptvAD+t44WVXaUjTBRcrpFeFlC8WCruUR456hw==
 
 lcid@^2.0.0:
   version "2.0.0"