Fixes #35: Pin libcrypto and libssl dylibs only on Catalina

[worldwise001]

Here's a possible fix to pin the versions at least on Catalina.

[wbond]

To get the Circle CI to pass we'll need to do this since Circle got rid of the 9.2.0 image: wbond/asn1crypto@d43d2b5.

[codecov]

Codecov Report

Merging #36 into master will decrease coverage by 0.18%.
The diff coverage is 75%.

@@            Coverage Diff             @@
##           master      #36      +/-   ##
==========================================
- Coverage   85.11%   84.92%   -0.19%     
==========================================
  Files          68       68              
  Lines        9420     9428       +8     
==========================================
- Hits         8018     8007      -11     
- Misses       1402     1421      +19

Impacted Files	Coverage Δ
oscrypto/_openssl/_libssl_cffi.py	87.5% <75%> (-2.5%)	⬇️
oscrypto/_openssl/_libcrypto_cffi.py	75% <75%> (ø)	⬆️
oscrypto/_win/tls.py	87.58% <0%> (-1.76%)	⬇️
oscrypto/_openssl/_libcrypto_ctypes.py	96.25% <0%> (-1.5%)	⬇️

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[wbond]

So right now the libcrypto bindings assume that when we see LibreSSL that we have an OpenSSL 1.0.1 compatible API.

It looks like in LibreSSL 2.7 they started adding OpenSSL 1.0.2 and 1.1.0 APIs. Because of this I think it would be safest if we default to libcrypto.42.dylib and libssl.44.dylib.

Here is the version info I got for libssl on Catalina:

libssl.35.dylib:libressl-2.2
libssl.43.dylib:libressl-2.5
libssl.44.dylib:libressl-2.6
libssl.46.dylib:libressl-2.8

[worldwise001]

Oh interesting. I can change that. I assumed the numbers were the same.

[worldwise001]

wow I am usually much better at catching linter problems.

[wbond]

Thanks for all of the digging and the fix!