Fix keys with utf 8

If wkd-srv runs with LANG=C (which is what happens in our images), ruby will default to US-ASCII as the default encoding.

OpenPGP Key uids should be UTF-8 strings, thus let's switch to UTF-8 as the default encoding.

Additionally, there are keys in the wild with broken character encoding. Thus let's be more on the safe side and enforce UTF-8 strings.

See:

• https://0xacab.org/schleuder/schleuder/-/issues/276
• https://0xacab.org/schleuder/schleuder/-/merge_requests/325
• https://0xacab.org/schleuder/schleuder/-/merge_requests/301

For more background on the details from another project.

Keys imported were fetched from the SKS network.