Update project mediaelement to 2.15.0

libgrabber updated project mediaelement to 2.15.0.

@johndyer

### Metadata information

```json
{
  "metadata": {
    "packageManager": "github",
    "name": "mediaelement",
    "repo": "johndyer/mediaelement",
    "files": {
      "basePath": "build/",
      "exclude": ["jquery.js", "DO NOT CHANGE THESE FILES. USE -src- FOLDER.txt"],
      "include": ["**/*"]
    },
    "path": "/home/jsdelivr/files/mediaelement",
    "localVersions": ["2.10.0", "2.10.1", "2.10.3", "2.11.0", "2.12.0", "2.13.1", "2.14.2"],
    "remoteVersions": ["2.4.3", "2.5.0", "2.6.3", "2.6.4", "2.6.5", "2.7.0", "2.8.0", "2.8.1", "2.8.2", "2.9.0", "2.9.1", "2.9.2", "2.9.3", "2.9.4", "2.9.5", "2.10.0", "2.10.1", "2.10.2", "2.10.3", "2.11.0", "2.11.1", "2.11.2", "2.11.3", "2.12.0", "2.13.0", "2.13.1", "2.13.2", "2.14.0", "2.14.2", "2.15.0"],
    "branchVersions": []
  },
  "version": "2.15.0",
  "updated": true,
  "updatePath": "/home/jsdelivr/files/mediaelement/2.15.0",
  "branch": "mediaelement/2.15.0"
}
```