Update readme with badges

Author: robabram

README.md

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+![Tests Completion Status](https://github.com/robabram/textual-thin-slider/actions/workflows/tests.yaml/badge.svg)
+![Coverage Status](https://raw.githubusercontent.com/robabram/textual-thin-slider/refs/heads/coverage-badge/coverage.svg?raw=true)
+![Supported Python Versions](https://img.shields.io/badge/python-v3.8%20|v3.9%20|%20v3.10%20|%20v3.11%20|%20v3.12%20|%20v3.13%20|%20v3.14-blue)
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 # Textual Thin Slider
 A thin slider widgit for the Textual UI platform. The this slider widgit is only 1 character tall and allows 
 fine control to choose a value within a range.