Try parallelism in py.test

Add requirements-dev.txt

Author: rocky

.github/workflows/ubuntu.yml

@@ -28,5 +28,5 @@ jobs:
         make develop
     - name: Test Mathics
       run: |
-        pip install pytest pexpect
-        make -j3 check
+        pip install -r requirements-dev.txt
+        PYTEST_WORKERS=-n3 make -j3 check

.github/workflows/windows.yml

@@ -31,5 +31,6 @@ jobs:
         python setup.py install
     - name: Test Mathics
       run: |
-        pip install pytest
+        pip install -r requirements-dev.txt
+        set PYTEST_WORKERS="-n3"
         make check

Makefile

@@ -57,7 +57,7 @@ clean:
 
 #: Run py.test tests. Use environment variable "o" for pytest options
 pytest:
-	py.test test $o
+	py.test $(PYTEST_WORKERS) test $o
 
 
 #: Run a more extensive pattern-matching test

requirements-dev.txt

@@ -0,0 +1,4 @@
+# Additional packages used in testing
+pytest
+pytest-xdist
+pexpect