Update GitHub CI badge (the link must have changed at some point) and…

… remove drone CI badge, which has been disable for a while

README.rst

@@ -10,10 +10,7 @@
 .. _Azure: https://dev.azure.com/franciscode-la-pena-manchon/hyperspy/_build?definitionId=1&_a=summary&view=branches
 
 .. |Github| image:: https://github.com/hyperspy/hyperspy/workflows/Tests/badge.svg
-.. _Github: https://github.com/hyperspy/hyperspy/actions?query=workflow%3ATests
-
-.. |Drone| image:: https://cloud.drone.io/api/badges/hyperspy/hyperspy/status.svg
-.. _Drone: https://cloud.drone.io/hyperspy/hyperspy
+.. _Github: https://github.com/hyperspy/hyperspy/actions/workflows/tests.yml
 
 .. |Codecov| image:: https://codecov.io/gh/hyperspy/hyperspy/branch/RELEASE_next_minor/graph/badge.svg
 .. _Codecov: https://codecov.io/gh/hyperspy/hyperspy