Merge pull request #391 from MetRonnie/pygraphviz

Workaround pygraphviz 1.8 bug for pip 22 / py 3.7

Author: oliver-sanders

.github/actions/install-dependencies/action.yml

@@ -21,9 +21,10 @@ runs:
           gsfonts \
           libfreetype6-dev \
           libfontconfig1-dev
+      # Explanation of some of these dependencies:
       # https://github.com/ImageMagick/ImageMagick/issues/374#issuecomment-279252866
 
     - shell: bash
       run: |
         echo "[command]pip install pygraphviz"
-        pip install pygraphviz
+        pip install "pygraphviz>1.0,!=1.8.0"