Add test using real files for zlib

[SaurabhK122]

For centos and ubuntu distros

[codecov-io]

Codecov Report

Merging #531 into master will decrease coverage by 9.77%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #531      +/-   ##
==========================================
- Coverage   86.06%   76.29%   -9.78%     
==========================================
  Files          52       56       +4     
  Lines        2210     2286      +76     
  Branches      449      465      +16     
==========================================
- Hits         1902     1744     -158     
- Misses        202      401     +199     
- Partials      106      141      +35     

Flag	Coverage Δ
#longtests	?
#ubuntutests	74.55% <ø> (-0.04%)	⬇️
#wintests	42.36% <ø> (-1.46%)	⬇️

Impacted Files	Coverage Δ
test/test_scanner.py	87.50% <ø> (-8.34%)	⬇️
test/test_json.py	59.37% <0.00%> (-31.25%)	⬇️
cve_bin_tool/cvedb.py	52.86% <0.00%> (-30.98%)	⬇️
cve_bin_tool/checkers/strongswan.py	72.22% <0.00%> (-27.78%)	⬇️
cve_bin_tool/checkers/xml2.py	54.90% <0.00%> (-27.46%)	⬇️
test/test_cli.py	80.37% <0.00%> (-19.63%)	⬇️
cve_bin_tool/checkers/kerberos.py	77.08% <0.00%> (-18.75%)	⬇️
cve_bin_tool/checkers/libjpeg.py	66.66% <0.00%> (-15.39%)	⬇️
cve_bin_tool/checkers/ffmpeg.py	85.71% <0.00%> (-14.29%)	⬇️
cve_bin_tool/checkers/binutils.py	80.55% <0.00%> (-13.89%)	⬇️
... and 19 more

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[SaurabhK122]

There appears to be a problem with syslog-ng checker, its signature test is failing while the tests I have added are passing.

[pdxjohnny]

Awesome! Thank you!