specify required tinyarray version

setup.py

@@ -637,7 +637,7 @@ def main():
                     'build_tut': build_tut,
                     'test': test},
           ext_modules=exts,
-          install_requires=['numpy >= 1.8.1', 'scipy >= 0.13.3', 'tinyarray'],
+          install_requires=['numpy >= 1.8.1', 'scipy >= 0.13.3', 'tinyarray >= 1.2.0'],
           extras_require={
               'plotting': 'matplotlib >= 1.3.1',
               # Ubuntu 16.04 is the oldest supported distro with python3-sympy