Fix CI; stop using Travis and AppVeyor

[tkf]

No description provided.

[codecov]

Codecov Report

Merging #456 (b3c12ae) into master (87c669e) will increase coverage by 1.47%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #456      +/-   ##
==========================================
+ Coverage   87.57%   89.05%   +1.47%     
==========================================
  Files          39       39              
  Lines        2246     2247       +1     
==========================================
+ Hits         1967     2001      +34     
+ Misses        279      246      -33     

Impacted Files	Coverage Δ
src/julia/tests/test_python_jl.py	100.00% <ø> (ø)
src/julia/julia_py.py	87.50% <0.00%> (-3.13%)	⬇️
src/julia/tools.py	77.77% <0.00%> (-0.88%)	⬇️
src/julia/find_libpython.py	80.86% <0.00%> (+0.61%)	⬆️
src/julia/pseudo_python_cli.py	80.87% <0.00%> (+1.09%)	⬆️
src/julia/core.py	83.63% <0.00%> (+1.51%)	⬆️
src/julia/tests/test_core.py	98.98% <0.00%> (+2.02%)	⬆️
src/julia/runtests.py	75.47% <0.00%> (+3.77%)	⬆️
src/julia/tests/test_compatible_exe.py	94.54% <0.00%> (+7.27%)	⬆️
src/julia/tests/test_utils.py	100.00% <0.00%> (+7.69%)	⬆️
... and 2 more

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