Don't require test deps for install

* closes #8

Author: michamos

setup.py

@@ -41,15 +41,16 @@
 
 install_requires = [
     'pyyaml>=6.0,<7.0',
-    'autosemver==0.5.5',
-    'isort<5.0.0',
     'six',
 ]
 
 setup_requires = [
     'autosemver==0.5.5',
 ]
 
+extras_require = {
+    'tests': tests_require,
+}
 
 setup(
     name='jsonschema2rst',
@@ -59,7 +60,7 @@
     license='GPLv2',
     keywords='jsonschema yaml rst parser documentation',
     packages=find_packages(),
-    install_requires=install_requires + tests_require,
+    install_requires=install_requires,
     tests_require=tests_require,
     setup_requires=setup_requires,
     long_description=readme,

tests/unit/test_rst_util.py

@@ -26,7 +26,6 @@
                         unicode_literals)
 
 import pytest
-
 from jsonschema2rst.rst_utils import (bold, bullet, container, emphasize,
                                       explicit_link, kv_field, line, literal,
                                       make_title)