I have investigated this issue and it seems to be a problem with wordpress.org. If you attempt to download the latest version it gives you
4.2.1. I have contacted the good people at wordpress.org and this should be sorted soon. I will keep you updated here about this.
In the meantime, if you wish to update to version 4.3.0, you can extract the files manually into your
wp-content/plugins/wallets directory. The latest plugin zip file can be downloaded from here: https://www.dashed-slug.net/downloads/
The other warning coming from the Monero coin adapter is not related and does not seem serious. I will investigate. Did you experience any issues with the Monero adapter? If possible, in the future, please post issues with the Monero adapter here: https://www.dashed-slug.net/forums/forum/monero-coin-adapter-extension-support/