Fix DNSStrField multiple values

[gpotter2]

fix https://github.com/secdev/scapy/issues/3866

[codecov[bot]]

Codecov Report

Merging #4256 (198e1a2) into master (cb7134c) will increase coverage by 1.28%. Report is 1 commits behind head on master. The diff coverage is 66.66%.

:exclamation: Current head 198e1a2 differs from pull request most recent head 32852d9. Consider uploading reports for the commit 32852d9 to get more accurate results

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4256      +/-   ##
==========================================
+ Coverage   49.66%   50.95%   +1.28%     
==========================================
  Files         342      349       +7     
  Lines       76288    81873    +5585     
==========================================
+ Hits        37892    41716    +3824     
- Misses      38396    40157    +1761     

Files	Coverage Δ
scapy/layers/dns.py	33.99% <66.66%> (+0.40%)	:arrow_up:

... and 124 files with indirect coverage changes