fix: remove github-post-release plugin

Author: bahmutov

package.json

@@ -75,8 +75,7 @@
           "release": "major"
         }
       ]
-    },
-    "generateNotes": "github-post-release"
+    }
   },
   "devDependencies": {
     "babel-plugin-transform-object-rest-spread": "6.26.0",
@@ -86,7 +85,6 @@
     "dependency-check": "3.1.0",
     "deps-ok": "1.4.0",
     "git-issues": "1.3.1",
-    "github-post-release": "1.13.1",
     "license-checker": "18.0.0",
     "mocha": "5.1.1",
     "nsp": "3.2.1",