Bump graceful-fs from 4.1.11 to 4.1.15

Bumps [graceful-fs](https://github.com/isaacs/node-graceful-fs) from 4.1.11 to 4.1.15.
- [Release notes](https://github.com/isaacs/node-graceful-fs/releases)
- [Commits](https://github.com/isaacs/node-graceful-fs/compare/v4.1.11...v4.1.15)

package.json

@@ -19,7 +19,7 @@
     "electron-installer-snap": "^3.0.0",
     "electron-rebuild": "^1.8.4",
     "file-loader": "^1.1.11",
-    "graceful-fs": "^4.1.11",
+    "graceful-fs": "^4.1.15",
     "html-loader": "0.4.4",
     "json-loader": "0.5.7",
     "node-abi": "^2.8.0",

yarn.lock

@@ -2599,11 +2599,7 @@ got@^6.7.1:
     unzip-response "^2.0.1"
     url-parse-lax "^1.0.0"
 
-graceful-fs@^4.1.11, graceful-fs@^4.1.3, graceful-fs@^4.1.9, graceful-fs@~4.1.11:
-  version "4.1.11"
-  resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.11.tgz#0e8bdfe4d1ddb8854d64e04ea7c00e2a026e5658"
-
-graceful-fs@^4.1.2, graceful-fs@^4.1.6:
+graceful-fs@^4.1.11, graceful-fs@^4.1.15, graceful-fs@^4.1.2, graceful-fs@^4.1.3, graceful-fs@^4.1.6, graceful-fs@^4.1.9, graceful-fs@~4.1.11:
   version "4.1.15"
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.15.tgz#ffb703e1066e8a0eeaa4c8b80ba9253eeefbfb00"