Explicitly declare PyDispatcher as dependencies

.travis.yml

@@ -48,6 +48,7 @@ install:
         tar -jxf ${PYPY_VERSION}.tar.bz2
         virtualenv --python="$PYPY_VERSION/bin/pypy3" "$HOME/virtualenvs/$PYPY_VERSION"
         source "$HOME/virtualenvs/$PYPY_VERSION/bin/activate"
+        $HOME/virtualenvs/$PYPY_VERSION/bin/pypy -m ensurepip --default-pip
       fi
   - pip install -U tox twine wheel codecov
 

tox.ini

@@ -77,7 +77,7 @@ deps =
     pyOpenSSL==18.0.0
     queuelib==1.4.2
     service_identity==16.0.0
-    Twisted==17.9.0
+    Twisted==20.3.0
     w3lib==1.17.0
     zope.interface==4.1.3
     -rtests/requirements-py3.txt
@@ -115,6 +115,9 @@ deps = {[testenv:pinned]deps}
 
 [testenv:pypy3]
 basepython = pypy3
+deps = 
+    {[testenv]deps}
+    PyDispatcher==2.0.5
 commands =
     py.test {posargs:--durations=10 docs scrapy tests}
 
@@ -124,7 +127,6 @@ commands = {[testenv:pypy3]commands}
 deps =
     {[pinned]deps}
     lxml==4.0.0
-    PyPyDispatcher==2.1.0
 
 [docs]
 changedir = docs