Revert "Make the tests pass with Python-Markdown 3.3"

Instead install Python-Markdown from git, where the breaking change was
fixed (see Python-Markdown/markdown#1033).

This reverts commit 39eb38f.

.travis.yml

@@ -19,7 +19,8 @@ addons:
     - libxkbcommon-x11-0
 install:
   - pip install --upgrade pip
-  - pip install PyQt5 Markdown pymdown-extensions docutils pyflakes chardet Pygments
+  - pip install git+https://github.com/Python-Markdown/markdown.git
+  - pip install PyQt5 pymdown-extensions docutils pyflakes chardet Pygments
   - pip install git+https://github.com/retext-project/pymarkups.git
 script:
   - xvfb-run -a -s "-screen 0 1024x768x24" python setup.py test

appveyor.yml

@@ -6,7 +6,8 @@ environment:
     - PYTHON: "C:\\Python38-x64"
 
 install:
-  - "%PYTHON%\\python.exe -m pip install PyQt5 Markdown docutils Markups"
+  - "%PYTHON%\\python.exe -m pip install git+https://github.com/Python-Markdown/markdown.git"
+  - "%PYTHON%\\python.exe -m pip install PyQt5 docutils Markups"
 
 build: off
 

tests/test_posmap.py

@@ -73,7 +73,7 @@ def test_highlightC(self):
         ```""")
         html = markdown(text, extensions=self.extensionsPosMap)
         expected = markdown(text, extensions=self.extensionsNoPosMap)
-        self.assertIn('<div class="c codehilite">', html)
+        self.assertIn('<div class="codehilite">', html)
         self.assertMultiLineEqual(html, expected)
 
     def test_highlightEmptyC(self):
@@ -83,7 +83,7 @@ def test_highlightEmptyC(self):
         ```""")
         html = markdown(text, extensions=self.extensionsPosMap)
         expected = markdown(text, extensions=self.extensionsNoPosMap)
-        self.assertIn('<div class="c codehilite">', html)
+        self.assertIn('<div class="codehilite">', html)
         self.assertMultiLineEqual(html, expected)
 
     def test_highlightPython(self):
@@ -94,7 +94,7 @@ def test_highlightPython(self):
         ```""")
         html = markdown(text, extensions=self.extensionsPosMap)
         expected = markdown(text, extensions=self.extensionsNoPosMap)
-        self.assertIn('<div class="python codehilite">', html)
+        self.assertIn('<div class="codehilite">', html)
         self.assertMultiLineEqual(html, expected)
 
     def test_highlightEmptyPython(self):
@@ -104,7 +104,7 @@ def test_highlightEmptyPython(self):
         ```""")
         html = markdown(text, extensions=self.extensionsPosMap)
         expected = markdown(text, extensions=self.extensionsNoPosMap)
-        self.assertIn('<div class="python codehilite">', html)
+        self.assertIn('<div class="codehilite">', html)
         self.assertMultiLineEqual(html, expected)
 
     def test_traditionalCodeBlock(self):