BPF filter: fix memory leak

[gpotter2]

The bpf_program created with compile_filter was never freed.

fix #4698

[codecov]

Codecov Report

❌ Patch coverage is 90.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 80.86%. Comparing base (ef72e1d) to head (88ad0c5).

Files with missing lines	Patch %	Lines
scapy/arch/linux/__init__.py	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4872      +/-   ##
==========================================
+ Coverage   80.48%   80.86%   +0.37%     
==========================================
  Files         368      368              
  Lines       90255    90260       +5     
==========================================
+ Hits        72645    72986     +341     
+ Misses      17610    17274     -336     

Files with missing lines	Coverage Δ
scapy/arch/bpf/core.py	83.33% <100.00%> (+0.28%)	⬆️
scapy/arch/common.py	69.84% <100.00%> (+1.50%)	⬆️
scapy/arch/linux/__init__.py	82.95% <80.00%> (-0.32%)	⬇️

... and 21 files with indirect coverage changes

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