[docs] Removed LGTM badges from README.

LGTM is deprecated.

README.md

@@ -11,8 +11,6 @@
 [![License: MPLv2.0][license-badge]](./LICENSE)
 [![Latest release][release-badge]][github releases]
 [![Debian Badge][debian-badge]][debian-package]
-[![LGTM Code Quality][lgtm-quality-badge]][lgtm-project]
-[![LGTM Alerts][lgtm-alerts-badge]][lgtm-project]
 [![codecov][codecov-badge]][codecov-project]
 [![Build Status Linux and macOS][travis-badge]][travis]
 [![Build Status Windows][appveyor-badge]][appveyor]
@@ -214,10 +212,6 @@ By contributing code to the SRT project, you agree to license your contribution
 [travis]: https://travis-ci.org/Haivision/srt
 [license-badge]: https://img.shields.io/badge/License-MPLv2.0-blue
 
-[lgtm-alerts-badge]: https://img.shields.io/lgtm/alerts/github/Haivision/srt
-[lgtm-quality-badge]: https://img.shields.io/lgtm/grade/cpp/github/Haivision/srt
-[lgtm-project]: https://lgtm.com/projects/g/Haivision/srt/
-
 [codecov-project]: https://codecov.io/gh/haivision/srt
 [codecov-badge]: https://codecov.io/gh/haivision/srt/branch/master/graph/badge.svg