ARROW-4601: [Python] Add license header to dockerignore

[xhochy]

No description provided.

[xhochy]

This happens when you have the pre-commit hook installed in all but one clone of Arrow 🤦‍♂️

[codecov-io]

Codecov Report

Merging #3679 into master will decrease coverage by 21.25%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #3679       +/-   ##
===========================================
- Coverage   87.78%   66.53%   -21.26%     
===========================================
  Files         689      324      -365     
  Lines       84023    48083    -35940     
  Branches     1081        0     -1081     
===========================================
- Hits        73758    31990    -41768     
- Misses      10154    16093     +5939     
+ Partials      111        0      -111

Impacted Files	Coverage Δ
cpp/src/arrow/pretty_print.h	0% <0%> (-100%)	⬇️
cpp/src/parquet/murmur3.h	0% <0%> (-100%)	⬇️
cpp/src/arrow/testing/util.h	0% <0%> (-100%)	⬇️
cpp/src/arrow/io/hdfs-internal.h	0% <0%> (-100%)	⬇️
cpp/src/arrow/util/sse-util.h	0% <0%> (-100%)	⬇️
cpp/src/arrow/testing/random.h	0% <0%> (-100%)	⬇️
cpp/src/parquet/hasher.h	0% <0%> (-100%)	⬇️
cpp/src/arrow/util/int-util.cc	0.39% <0%> (-99.21%)	⬇️
cpp/src/arrow/ipc/json-simple.cc	0.41% <0%> (-98.76%)	⬇️
cpp/src/arrow/testing/random.cc	1.96% <0%> (-98.04%)	⬇️
... and 511 more

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[xhochy]

+1

[kszucs]

Your commit was flagged with "skip ci", so it was green.