fix(dist): add to the released tarball also files for testing

Fixes: CodSpeedHQ#68

Author: mcepl

MANIFEST.in

@@ -0,0 +1,14 @@
+include tests/conftest.py
+include tests/examples/*
+# include src/SWIG/*.h
+# include src/SWIG/*.def
+# recursive-include tests *.py *.pem *.der *.b64 README *.pgp *.dat *.p7* *.crt *.txt
+# recursive-include doc *
+# recursive-include contrib *
+# recursive-exclude .keys *
+# include INSTALL.rst
+# include README.rst
+# include CHANGES
+# include LICENCE
+# include src/SWIG/_m2crypto_wrap.c
+# include src/M2Crypto/m2crypto.py