Drop support for symfony 3

[core23]

No description provided.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@08ddf20). Click here to learn what that means.
The diff coverage is 100%.

@@           Coverage Diff           @@
##             master    #37   +/-   ##
=======================================
  Coverage          ?   100%           
  Complexity        ?     48           
=======================================
  Files             ?     10           
  Lines             ?    140           
  Branches          ?      0           
=======================================
  Hits              ?    140           
  Misses            ?      0           
  Partials          ?      0

Impacted Files	Coverage Δ	Complexity Δ
src/DependencyInjection/Configuration.php	100% <100%> (ø)	3 <0> (?)

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