Removed some legacy garbage (#3502)

diff --git a/tox.ini b/tox.ini
index 0e75011..136b4cc 100644
--- a/tox.ini
+++ b/tox.ini
@@ -9,8 +9,6 @@
     coverage
     ./vectors
 passenv = ARCHFLAGS LDFLAGS CFLAGS INCLUDE LIB LD_LIBRARY_PATH USERNAME
-setenv =
-    CRYPTOGRAPHY_ALLOW_OPENSSL_100=1
 commands =
     pip list
     # We use parallel mode and then combine here so that coverage.py will take