Update version shield
<h1 align="center"> LittlevGL - Open-source Embedded GUI Library</h1>
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<a href="https://github.com/littlevgl/lvgl/blob/master/LICENCE.txt"><img src="https://img.shields.io/badge/licence-MIT-blue.svg"></a>
-<a href="https://github.com/littlevgl/lvgl/releases/tag/v6.0"><img src="https://img.shields.io/badge/version-6.0-blue.svg"></a>
+<a href="https://github.com/littlevgl/lvgl/releases/tag/v6.1.2"><img src="https://img.shields.io/badge/version-6.1.2-blue.svg"></a>
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