No longer need PyYAML. Simpfiy Windows CI test

.github/workflows/windows.yml

@@ -25,17 +25,7 @@ jobs:
         python -m pip install wheel
         choco install llvm
         set LLVM_DIR="C:\Program Files\LLVM"
-        pip install llvmlite
-        pip install numpy
-        pip install sympy
-        pip install pillow
-        pip install scikit-image
-        pip install requests
-        pip install wordcloud
-        pip install PyYAML
-        pip install palettable
-        pip install mpmath
-        pip install mathics_scanner
+        pip install -e .
     - name: Install Mathics
       run: |
         python setup.py install

setup.py

@@ -91,7 +91,6 @@ def read(*rnames):
     "requests",
     "scikit-image",
     "wordcloud",  # Used in builtin/image.py by WordCloud()
-    "PyYAML",  # Used in mathics.core.characters
 ]