The old key was overwritten during a machine migration and the current
worker key is no longer valid. To create new valid worker certificates
this commit adds a new CA pubkey.
To update running OpenWrt devices via a client one needs to force
install it or upgrade to the latest version of
`attendedsysupgrade-common` - I'm sorry for the inconvenience.
This change is only related to the `usign` pubkey and `ucert`
certificate which is used to sign all created images on the server.
While at it, use INSTALL_DATA instead of INSTALL_BIN.
Signed-off-by: Paul Spooren <mail@aparcar.org>
