requirements: update 'mypy'

(plus some dependencies)

Changelog:
- 0.670 (2019-02-08)
  https://github.com/python/mypy/releases/tag/v0.670
- 0.660 (2010-01-16)
  https://github.com/python/mypy/releases/tag/v0.660

Code diff:
python/mypy@v0.660...v0.670

Author: glarrain

requirements/test.txt

@@ -4,7 +4,7 @@
 # Required packages:
 coverage==4.5.1
 flake8==3.5.0
-mypy==0.650
+mypy==0.670
 #requests-mock==1.5.2
 #tox==3.2.1
 
@@ -26,5 +26,5 @@ mypy-extensions==0.4.1
 #py==1.5.4
 pycodestyle==2.3.1
 pyflakes==1.6.0
-typed-ast==1.1.0
+typed-ast==1.3.1
 #virtualenv==16.0.0