Fix solidity public calls url

Author: r0qs

docs/contributing.rst

@@ -32,7 +32,7 @@ the team and contributors are working on, you can join our public team call:
 
 - Wednesdays at 3PM CET/CEST.
 
-The call takes place on `Jitsi <https://meet.ethereum.org/solidity>`_.
+The call takes place on `Jitsi <https://meet.solidity.org>`_.
 
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