Update dependency graphql to v15

package.json

@@ -7,7 +7,7 @@
   "license": "MIT",
   "dependencies": {
     "apollo-client": "2.6.4",
-    "graphql": "14.5.8",
+    "graphql": "15.3.0",
     "react": "16.10.2",
     "react-apollo": "3.1.3",
     "react-apollo-hooks": "0.5.0",

yarn.lock

@@ -1996,12 +1996,10 @@ [email protected]:
     iterall "^1.1.3"
     uuid "^3.1.0"
 
-[email protected]:
-  version "14.5.8"
-  resolved "https://registry.yarnpkg.com/graphql/-/graphql-14.5.8.tgz#504f3d3114cb9a0a3f359bbbcf38d9e5bf6a6b3c"
-  integrity sha512-MMwmi0zlVLQKLdGiMfWkgQD7dY/TUKt4L+zgJ/aR0Howebod3aNgP5JkgvAULiR2HPVZaP2VEElqtdidHweLkg==
-  dependencies:
-    iterall "^1.2.2"
+[email protected]:
+  version "15.3.0"
+  resolved "https://registry.yarnpkg.com/graphql/-/graphql-15.3.0.tgz#3ad2b0caab0d110e3be4a5a9b2aa281e362b5278"
+  integrity sha512-GTCJtzJmkFLWRfFJuoo9RWWa/FfamUHgiFosxi/X1Ani4AVWbeyBenZTNX6dM+7WSbbFfTo/25eh0LLkwHMw2w==
 
 har-schema@^2.0.0:
   version "2.0.0"
@@ -2409,7 +2407,7 @@ isstream@~0.1.2:
   resolved "https://registry.yarnpkg.com/isstream/-/isstream-0.1.2.tgz#47e63f7af55afa6f92e1500e690eb8b8529c099a"
   integrity sha1-R+Y/evVa+m+S4VAOaQ64uFKcCZo=
 
-iterall@^1.1.3, iterall@^1.2.2:
+iterall@^1.1.3:
   version "1.2.2"
   resolved "https://registry.yarnpkg.com/iterall/-/iterall-1.2.2.tgz#92d70deb8028e0c39ff3164fdbf4d8b088130cd7"
   integrity sha512-yynBb1g+RFUPY64fTrFv7nsjRrENBQJaX2UL+2Szc9REFrSNm1rpSXHGzhmAy7a9uv3vlvgBlXnf9RqmPH1/DA==