Bump xterm from 4.15.0 to 4.18.0 (#5091)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

package.json

@@ -404,7 +404,7 @@
     "webpack-cli": "^4.9.2",
     "webpack-dev-server": "^4.7.4",
     "webpack-node-externals": "^3.0.0",
-    "xterm": "^4.15.0",
+    "xterm": "^4.18.0",
     "xterm-addon-fit": "^0.5.0"
   }
 }