fix: should use graphql v15 at all levels of dependency (#6192)

It causes peer dependency warnings because of several ill-maintained
apollo packages, but let's just ignore them.
Fixes #6191

package.json

@@ -55,7 +55,7 @@
     "execa": "^1.0.0",
     "geckodriver": "^1.20.0",
     "globby": "^11.0.1",
-    "graphql": "^14.6.0",
+    "graphql": "^15.4.0",
     "http-server": "^0.12.3",
     "inquirer": "^7.1.0",
     "jest": "^26.6.3",

packages/@vue/cli-ui/package.json

@@ -44,7 +44,7 @@
     "fkill": "^7.0.1",
     "fs-extra": "^9.0.1",
     "globby": "^11.0.1",
-    "graphql": "^14.6.0",
+    "graphql": "^15.4.0",
     "graphql-subscriptions": "^1.1.0",
     "graphql-tag": "^2.10.3",
     "graphql-type-json": "^0.3.1",

yarn.lock

@@ -11596,18 +11596,11 @@ graphql-ws@3.1.0:
   resolved "https://registry.yarnpkg.com/graphql-ws/-/graphql-ws-3.1.0.tgz#cd09d385a21ab88af4c226da79c19351df9b27e8"
   integrity sha512-zbex3FSiFz0iRgfkzDNWpOY/sYWoX+iZ5XUhakaDwOh99HSuk8rPt5suuxdXUVzEg5TGQ9rwzNaz/+mTPtS0yg==
 
-"graphql@14.0.2 - 14.2.0 || ^14.3.1 || ^15.0.0", graphql@^15.1.0, graphql@^15.3.0:
+"graphql@14.0.2 - 14.2.0 || ^14.3.1 || ^15.0.0", graphql@^15.1.0, graphql@^15.3.0, graphql@^15.4.0:
   version "15.4.0"
   resolved "https://registry.yarnpkg.com/graphql/-/graphql-15.4.0.tgz#e459dea1150da5a106486ba7276518b5295a4347"
   integrity sha512-EB3zgGchcabbsU9cFe1j+yxdzKQKAbGUWRb13DsrsMN1yyfmmIq+2+L5MqVWcDCE4V89R5AyUOi7sMOGxdsYtA==
 
-graphql@^14.6.0:
-  version "14.7.0"
-  resolved "https://registry.yarnpkg.com/graphql/-/graphql-14.7.0.tgz#7fa79a80a69be4a31c27dda824dc04dac2035a72"
-  integrity sha512-l0xWZpoPKpppFzMfvVyFmp9vLN7w/ZZJPefUicMCepfJeQ8sMcztloGYY9DfjVPo6tIUDzU5Hw3MUbIjj9AVVA==
-  dependencies:
-    iterall "^1.2.2"
-
 gray-matter@^2.0.0:
   version "2.1.1"
   resolved "https://registry.yarnpkg.com/gray-matter/-/gray-matter-2.1.1.tgz#3042d9adec2a1ded6a7707a9ed2380f8a17a430e"
@@ -13076,7 +13069,7 @@ isurl@^1.0.0-alpha5:
     has-to-string-tag-x "^1.2.0"
     is-object "^1.0.1"
 
-iterall@^1.1.3, iterall@^1.2.1, iterall@^1.2.2:
+iterall@^1.1.3, iterall@^1.2.1:
   version "1.3.0"
   resolved "https://registry.yarnpkg.com/iterall/-/iterall-1.3.0.tgz#afcb08492e2915cbd8a0884eb93a8c94d0d72fea"
   integrity sha512-QZ9qOMdF+QLHxy1QIpUHUU1D5pS2CG2P69LF6L6CPjPYA/XMOmKV3PZpawHoAjHNyB0swdVTRxdYT4tbBbxqwg==