chore: reset cosmos-sdk buf dependencies to 0.50.0

Author: bdeneux

proto/buf.yaml

@@ -1,7 +1,7 @@
 version: v1
 name: buf.build/axone-protocol/axoned
 deps:
-  - buf.build/cosmos/cosmos-sdk:v0.50.4
+  - buf.build/cosmos/cosmos-sdk:v0.50.0
   - buf.build/cosmos/cosmos-proto
   - buf.build/cosmos/gogo-proto
   - buf.build/googleapis/googleapis