Fix centos 7 Dockerfile

[iamluc]

Description

centos 7 is EOL and mirrorlist.centos.org does not resolve anymore

Reviewer checklist

• Test coverage seems ok.
• Appropriate labels assigned.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.95%. Comparing base (eab1560) to head (a4ed469).
Report is 1 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #2738      +/-   ##
============================================
- Coverage     79.52%   77.95%   -1.57%     
  Complexity     2216     2216              
============================================
  Files           201      227      +26     
  Lines         22595    26612    +4017     
  Branches          0      988     +988     
============================================
+ Hits          17969    20746    +2777     
- Misses         4626     5340     +714     
- Partials          0      526     +526     

Flag	Coverage Δ
appsec-extension	69.13% <ø> (?)
tracer-extension	78.82% <ø> (ø)
tracer-php	80.54% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

see 26 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update eab1560...a4ed469. Read the comment docs.