Added pipeline badges

README.md

+![Pipeline status](https://gitlab.eclipse.org/eclipse/aidge/aidge_core/badges/main/pipeline.svg?ignore_skipped=true) ![C++ coverage](https://gitlab.eclipse.org/eclipse/aidge/aidge_core/badges/main/coverage.svg?job=coverage:ubuntu_cpp&key_text=C%2B%2B+coverage&key_width=90) ![Python coverage](https://gitlab.eclipse.org/eclipse/aidge/aidge_core/badges/main/coverage.svg?job=coverage:ubuntu_python&key_text=Python+coverage&key_width=100)
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 # Aidge Core library
 
 You can find here the C++ code of the Core library of Aidge.