Drop Node v15 (#3055)

Author: IvanGoncharov

.github/workflows/ci.yml

@@ -139,7 +139,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        node_version_to_setup: [12, 14, 15, 16]
+        node_version_to_setup: [12, 14, 16]
     steps:
       - name: Checkout repo
         uses: actions/checkout@v2

integrationTests/node/package.json

@@ -7,7 +7,6 @@
     "graphql": "file:../graphql.tgz",
     "node-12": "npm:[email protected]",
     "node-14": "npm:[email protected]",
-    "node-15": "npm:[email protected]",
     "node-16": "npm:[email protected]"
   }
 }

package.json

@@ -21,7 +21,7 @@
     "graphql-js"
   ],
   "engines": {
-    "node": "^12.20.0 || ^14.15.0 || ^15.9.0 || >=16.0.0"
+    "node": "^12.22.0 || ^14.16.0 || >=16.0.0"
   },
   "scripts": {
     "preversion": ". ./resources/checkgit.sh && npm ci",