Restore pinned dependencies in tox.ini

tox.ini

@@ -66,21 +66,17 @@ commands =
 [pinned]
 deps =
     -ctests/constraints.txt
-    #using cryptography-2.3.1 to solve dependencies conflict on pip20.2>=
-    cryptography==2.3.1
+    cryptography==2.0
     cssselect==0.9.1
     itemadapter==0.1.0
     parsel==1.5.0
     Protego==0.1.15
-    !pypy3: PyDispatcher==2.0.5
-    #using pyOpenSSL<18.1 to solve dependencies conflict with mitmproxy on pip20.2>=
-    pyOpenSSL==18.0.0
+    pyOpenSSL==16.2.0
     queuelib==1.4.2
     service_identity==16.0.0
-    Twisted==20.3.0
+    Twisted==17.9.0
     w3lib==1.17.0
-    #zope.interface==5.1.2 to resolve conflict with Twisted==20.3.0
-    zope.interface==5.1.2
+    zope.interface==4.1.3
     -rtests/requirements-py3.txt
     # Extras
     botocore==1.4.87
@@ -91,6 +87,7 @@ deps =
 deps =
     {[pinned]deps}
     lxml==3.5.0
+    PyDispatcher==2.0.5
     
 [testenv:windows-pinned]
 basepython = python3
@@ -99,6 +96,7 @@ deps =
     # First lxml version that includes a Windows wheel for Python 3.6, so we do
     # not need to build lxml from sources in a CI Windows job:
     lxml==3.8.0
+    PyDispatcher==2.0.5
 
 [testenv:extra-deps]
 deps =