Explicitly pin ZEO bellow 5.0.0a0

Also, Appveyor is special and I forgot that again.

setup.py

@@ -86,6 +86,7 @@ def get_long_description():
     package_dir={'': 'src'},
     install_requires=[
         "ZODB3",
+        "ZEO < 5.0.0a0",
         "zope.app.pagetemplate",
         "zope.app.publication",
         "zope.component",

tox.ini

@@ -15,19 +15,16 @@ commands =
 # problems that break the build.  My hope is that if 'persistent' is already
 # installed (not just downloaded) then setup.py egg_info will find it and use
 # it instead of attempting to download it again.
-# Install ZEO because zodbbrowser depends on ZODB3 which depends on ZEO >=
-# 4.0.0dev which tells pip that prereleases are fine, which makes it go and
-# download ZEO 5.0.0a2, which is broken on windows, somehow.
 # Upgrade pip because otherwise we can't find lxml wheels because the ABI tag
 # format changed or something.
 deps =
     zope.testrunner
     persistent
-    ZEO
     pip
 install_command = python -m pip install -U {opts} {packages}
 
 [testenv:py]
+install_command = python -m pip install -U {opts} {packages}
 commands =
     python --version
     zope-testrunner --test-path=src --tests-pattern='^f?tests$' {posargs}