DEVELOPERS: remove Daniel Nystrom

<daniel.nystrom@timeterminal.se>: host ASPMX.L.GOOGLE.COM[172.217.218.26] said:
    550-5.1.1 The email account that you tried to reach does not exist. Please
    try 550-5.1.1 double-checking the recipient's email address for typos or
    550-5.1.1 unnecessary spaces. Learn more at 550 5.1.1
    https://support.google.com/mail/?p=NoSuchUser

 o14si10209151edi.116 - gsmtp
    (in reply to RCPT TO command)

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>