Fix build on manylinux1

Author: mayeut

requirements-dev.txt

@@ -11,3 +11,8 @@ twine
 virtualenv>=15.0.3
 wheel>=0.34
 wheeltools
+
+# need to pin cryptography for manylinux1 builds
+# cryptography only provides manylinux2010 wheels since 3.4.0
+# because of the lack of a decent rust compiler on manylinux1
+cryptography~=3.3.2 ; sys_platform=="linux" and platform_machine in "i386, i486, i586, i686, x86_64"