Bump xterm-addon-webgl from 0.6.0 to 0.8.0

Bumps [xterm-addon-webgl](https://github.com/xtermjs/xterm.js) from 0.6.0 to 0.8.0.
- [Release notes](https://github.com/xtermjs/xterm.js/releases)
- [Commits](https://github.com/xtermjs/xterm.js/compare/0.6...0.8)

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

package.json

@@ -55,7 +55,7 @@
     "xterm-addon-ligatures": "^0.3.0",
     "xterm-addon-search": "^0.7.0",
     "xterm-addon-web-links": "^0.4.0",
-    "xterm-addon-webgl": "^0.6.0"
+    "xterm-addon-webgl": "^0.8.0"
   },
   "devDependencies": {
     "@ava/babel": "1.0.1",