More fixes

- Dropped Python 2.7 testing, not sure why this was on the repo but
  we probably don't want that. Set python_requires to 3.7 and made
  CI test 3.7 and 3.9 for now.
- Converted to pytest for its simplicity
- Made tests write output files to a temporary path to keep things
  from getting cluttered.
- Cleaned up some of the imports
- Added a fix to install typing_compat and typing_extensions when
  using Python 3.7.

Author: davidt0x

.github/workflows/ci.yml

@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: [ 2.7, 3.7 , 3.9 ]
+        python-version: [ 3.7 , 3.9 ]
 
     steps:
     - uses: actions/checkout@v2

setup.cfg

@@ -39,8 +39,10 @@ install_requires =
    attrs
    cattrs
    docstring-parser
+   typing_extensions;python_version<'3.8'
+   typing_compat;python_version<'3.8'
 
-python_requires = >=3.6
+python_requires = >=3.7
 include_package_data = True
 package_dir =
     =src

test_all.sh

@@ -8,5 +8,4 @@ python document.py
 
 cd ..
 
-cd modelspec/test
-pytest -v
+pytest tests