Mail url collector fix

[tomas321]

The Shadowserver mail body was changed to bytes object, which could not be parsed.

[ghost]

Did you want to only submit 406f7aa4de4d1ca12cfe3372710224cc9eb85346?

[tomas321]

Yes, only the change in process function

[codecov-io]

Codecov Report

Merging #1367 into develop will increase coverage by 0.14%.
The diff coverage is 95.31%.

@@             Coverage Diff             @@
##           develop    #1367      +/-   ##
===========================================
+ Coverage    74.48%   74.63%   +0.14%     
===========================================
  Files          301      302       +1     
  Lines        13631    13656      +25     
  Branches      1844     1841       -3     
===========================================
+ Hits         10153    10192      +39     
+ Misses        3070     3057      -13     
+ Partials       408      407       -1

Impacted Files	Coverage Δ
...ts/bots/parsers/shadowserver/test_http-scanners.py	100% <100%> (ø)
intelmq/bots/parsers/shadowserver/config.py	89.07% <100%> (+0.28%)	⬆️
...sts/bots/parsers/shadowserver/test_ics-scanners.py	100% <100%> (ø)
...ts/parsers/shadowserver/test_amplification-ddos.py	100% <100%> (ø)
intelmq/bots/collectors/mail/collector_mail_url.py	20.23% <25%> (+0.59%)	⬆️
intelmq/bots/outputs/restapi/output.py	60% <0%> (-4.71%)	⬇️
intelmq/tests/bots/parsers/twitter/test_parser.py	100% <0%> (ø)	⬆️
intelmq/bots/collectors/mail/lib.py
...ntelmq/bots/collectors/mail/collector_mail_body.py
... and 6 more

[ghost]

I also adapted the patch to the maintenance branch

I cherry-picked the one commit for develop.

Thanks for the patch