Revert ""Fix egg on dependency links [SKIP CI].""

This reverts commit daf872920d.

.drone.yml

@@ -41,10 +41,4 @@ matrix:
           DATABASE: sqlite
         - IMAGE: python:3.7
           TOXENV: py37
-          DATABASE: postgresql
-        - IMAGE: python:3.8
-          TOXENV: py38
-          DATABASE: sqlite
-        - IMAGE: python:3.8
-          TOXENV: py38
           DATABASE: postgresql

tox.ini

@@ -1,10 +1,10 @@
 [tox]
-envlist = {py36,py37,py38}-{sqlite,postgresql},pypy3-{sqlite,postgresql}
+envlist = {py36,py37}-{sqlite,postgresql},pypy3-{sqlite,postgresql}
 
 [testenv]
 commands = {envpython} setup.py test
 deps =
-    {py36,py37,py38}-postgresql: psycopg2 >= 2.5
+    {py36,py37}-postgresql: psycopg2 >= 2.5
     pypy3-postgresql: psycopg2cffi >= 2.5
     {py36}-sqlite: sqlitebck
 setenv =