dotnet-bump: remove "Update to" from the commit message

Signed-off-by: Ilya Leoshkevich <[email protected]>

Author: iii-i

dotnet-bump

@@ -131,5 +131,5 @@ done
 } >>dotnet-versions
 
 git add dotnet-versions
-git commit --allow-empty --message="Update to v$installer_version" --signoff
+git commit --allow-empty --message="v$installer_version" --signoff
 git tag "v$installer_version"