add numpy install to travis

[sangshuduo]

[TD-630]

[codecov-commenter]

Codecov Report

Merging #2269 into develop will increase coverage by 1.50%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop    #2269      +/-   ##
===========================================
+ Coverage    54.31%   55.81%   +1.50%     
===========================================
  Files          123      123              
  Lines        42315    43277     +962     
===========================================
+ Hits         22982    24154    +1172     
+ Misses       19333    19123     -210     

Impacted Files	Coverage Δ
src/util/src/tskiplist.c	61.14% <0.00%> (-8.45%)	⬇️
src/tsdb/src/tsdbMeta.c	78.03% <0.00%> (-3.42%)	⬇️
src/client/src/tscFunctionImpl.c	21.27% <0.00%> (-1.41%)	⬇️
src/mnode/src/mnodeTable.c	58.38% <0.00%> (+0.20%)	⬆️
src/query/src/qextbuffer.c	39.80% <0.00%> (+0.32%)	⬆️
src/query/src/qExecutor.c	70.45% <0.00%> (+0.37%)	⬆️
src/query/src/qparserImpl.c	72.44% <0.00%> (+0.38%)	⬆️
src/mnode/src/mnodeProfile.c	14.58% <0.00%> (+0.53%)	⬆️
src/tsdb/src/tsdbRWHelper.c	76.79% <0.00%> (+0.53%)	⬆️
src/tsdb/src/tsdbMain.c	57.52% <0.00%> (+0.53%)	⬆️
... and 28 more

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