Broken build due to OpenPGP key servers problem

[xmikus01]

Latest versions of all supported branches aren't uploaded correctly (empty directory):

• https://unofficial-builds.nodejs.org/download/release/v16.4.1/
• https://unofficial-builds.nodejs.org/download/release/v14.17.2/
• https://unofficial-builds.nodejs.org/download/release/v12.22.2/

There are problem with OpenPGP keys according to logs:

• https://unofficial-builds.nodejs.org/logs/202107011543-v16.4.1/fetch-source.log
• https://unofficial-builds.nodejs.org/logs/202107011549-v14.17.2/fetch-source.log
• https://unofficial-builds.nodejs.org/logs/202107011554-v12.22.2/fetch-source.log

Problems with OpenPGP key servers were discussed and solved in:

• chore: Use openpgp and Ubuntu keyservers docker-node#1510
• gpg: keyserver receive failed: No keyserver available since sks-keyservers.net no longer publishes DNS addresses docker-node#1500