Bump xterm from 3.15.0-beta80 to 3.15.0-beta81 in /terminus-terminal

Bumps [xterm](https://github.com/xtermjs/xterm.js) from 3.15.0-beta80 to 3.15.0-beta81.
- [Release notes](https://github.com/xtermjs/xterm.js/releases)
- [Commits](https://github.com/xtermjs/xterm.js/commits)
Signed-off-by: Ndependabot-preview[bot] <support@dependabot.com>

terminus-terminal/package.json

@@ -28,7 +28,7 @@
     "runes": "^0.4.2",
     "slug": "^1.1.0",
     "uuid": "^3.3.2",
-    "xterm": "3.15.0-beta80",
+    "xterm": "3.15.0-beta81",
     "xterm-addon-fit": "^0.1.0-beta3",
     "xterm-addon-ligatures": "^0.1.0-beta-2",
     "xterm-addon-search": "^0.2.0-beta1",

terminus-terminal/yarn.lock

@@ -188,10 +188,10 @@ xterm-addon-webgl@^0.2.0-beta1:
   resolved "https://registry.yarnpkg.com/xterm-addon-webgl/-/xterm-addon-webgl-0.2.0-beta5.tgz#79d97c21bb09c34c6aca6f4e72afe8085f8a77dc"
   integrity sha512-TR6071ZWQ2l0E/P7KedDfsGCW21BWCfemiV/swBF+X/BiRzzsZlJXpZP62jR/XV0/J7r1SMVPSIP5j8TMCoDmw==
 
-xterm@3.15.0-beta80:
-  version "3.15.0-beta80"
-  resolved "https://registry.yarnpkg.com/xterm/-/xterm-3.15.0-beta80.tgz#6a17eea9c9d05667acdede641cfb76a7c0d0a3cd"
-  integrity sha512-nidVf1uDiOa5BsYR4/uK61qsVeo/gsuvgL6HeVthcLO3WkObGpsXNaZmIFmLmgsyA4RROpjSvKipTFD8mPt+Jg==
+xterm@3.15.0-beta81:
+  version "3.15.0-beta81"
+  resolved "https://registry.yarnpkg.com/xterm/-/xterm-3.15.0-beta81.tgz#1a4c01467776753d1cebee8bfafb6c4ee7f9d543"
+  integrity sha512-tyADfzVm55CAxCIXWJzHWMCRPYcJQp8hO/85KLxRuVjCdeuVgRn/9U9VKypNd9DJkZGsf1rONkQMnG6IDZ1DEQ==
 
 yallist@^2.1.2:
   version "2.1.2"