Bump xterm from 4.7.0 to 4.8.1

Bumps [xterm](https://github.com/xtermjs/xterm.js) from 4.7.0 to 4.8.1.
- [Release notes](https://github.com/xtermjs/xterm.js/releases)
- [Commits](https://github.com/xtermjs/xterm.js/compare/4.7.0...4.8.1)

Signed-off-by: dependabot[bot] <support@github.com>

package.json

@@ -50,7 +50,7 @@
     "stylis": "3.5.4",
     "uuid": "8.2.0",
     "webpack-cli": "3.3.12",
-    "xterm": "^4.7.0",
+    "xterm": "^4.8.1",
     "xterm-addon-fit": "^0.4.0",
     "xterm-addon-ligatures": "^0.3.0",
     "xterm-addon-search": "^0.7.0",