Update gnupg to 2.2.6

• gpg,gpgsm: New option --request-origin to pretend requests coming from a browser or a remote site.
• gpg: Fix race condition on trustdb.gpg updates due to too early released lock. [#3839]
• gpg: Emit FAILURE status lines in almost all cases. [#3872]
• gpg: Implement --dry-run for --passwd to make checking a key's passphrase straightforward.
• gpg: Make sure to only accept a certification capable key for key signatures. [#3844]
• gpg: Better user interaction in --card-edit for the factory-reset sub-command.
• gpg: Improve changing key attributes in --card-edit by adding an explicit "key-attr" sub-command. [#3781]
• gpg: Print the keygrips in the --card-status.
• scd: Support KDF DO setup. [#3823]
• scd: Fix some issues with PC/SC on Windows. [#3825]
• scd: Fix suspend/resume handling in the CCID driver.
• agent: Evict cached passphrases also via a timer. [#3829]
• agent: Use separate passphrase caches depending on the request origin. [#3858]
• ssh: Support signature flags. [#3880]
• dirmngr: Handle failures related to missing IPv6 support gracefully. [#3331]
• Fix corner cases related to specified home directory with drive letter on Windows. [#3720]
• Allow the use of UNC directory names as homedir. [#3818]