arch: import read_nameservers on illumos-based systems too

[evverx]

to prevent it from failing there with:

  ...
    from scapy.all import *
  File "/root/scapy/scapy/all.py", line 16, in <module>
    from scapy.arch import *
AttributeError: module 'scapy.arch' has no attribute 'read_nameservers'

With this patch applied run_scapy no longer fails and dns_resolve works as expected:

>>> sys.platform
'sunos5'
>>> dns_resolve('example.com')
[<DNSRR  rrname=b'example.com.' type=A cacheflush=0 rclass=IN ttl=174 rdata=8.47.69.4 |>,
 <DNSRR  rrname=b'example.com.' type=A cacheflush=0 rclass=IN ttl=174 rdata=8.6.112.4 |>]

F403 isn't needed there (it was probably copied from the next line) so it was removed to avoid hitting E501 line too long (89 > 88 characters).

It's a follow-up to 528626a

AI-Assisted: no

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 80.30%. Comparing base (5f271b5) to head (350b9f4).

Files with missing lines	Patch %	Lines
scapy/arch/solaris.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #5030      +/-   ##
==========================================
- Coverage   80.30%   80.30%   -0.01%     
==========================================
  Files         386      386              
  Lines       96127    96127              
==========================================
- Hits        77192    77191       -1     
- Misses      18935    18936       +1     

Files with missing lines	Coverage Δ
scapy/arch/solaris.py	0.00% <0.00%> (ø)

... and 1 file with indirect coverage changes

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[gpotter2]

Thanks for the PR !