fix: remove electron 21 prebuilds

Author: aminya

package.json

@@ -27,8 +27,8 @@
   "scripts": {
     "install": "node-gyp-build || npm run build:libzmq",
     "build:libzmq": "node-gyp rebuild",
-    "prebuildify": "prebuildify -t 18.12.1 -t 16.18.1 -t 14.21.1 -t 12.22.12 -t [email protected] -t [email protected] --strip",
-    "prebuildify-ia32": "prebuildify --arch=ia32 -t 18.12.1 -t 16.18.1 -t 14.21.1 -t 12.22.12 -t [email protected] -t [email protected]  --strip",
+    "prebuildify": "prebuildify -t 18.12.1 -t 16.18.1 -t 14.21.1 -t 12.22.12 -t [email protected] --strip",
+    "prebuildify-ia32": "prebuildify --arch=ia32 -t 18.12.1 -t 16.18.1 -t 14.21.1 -t 12.22.12 -t [email protected] --strip",
     "build:docs": "jsdoc -R README.md -d docs lib/*.js",
     "test": "mocha --expose-gc --slow 300",
     "test:electron": "electron-mocha --slow 300",