update(PyUp): scheduled monthly dependency update for April (#76)

* Update attrs from 18.2.0 to 19.1.0

* Update certifi from 2018.11.29 to 2019.3.9

* Update coverage from 4.5.2 to 4.5.3

* Update more-itertools from 6.0.0 to 7.0.0

* Update pytest from 4.3.0 to 4.4.0

requirements.txt

@@ -1,23 +1,23 @@
 argh==0.26.2
 atomicwrites==1.3.0
-attrs==18.2.0
-certifi==2018.11.29
+attrs==19.1.0
+certifi==2019.3.9
 chardet==3.0.4
 codacy-coverage==1.3.11
 codeclimate-test-reporter==0.2.3
 colorama==0.4.1
 colored==1.3.93
-coverage==4.5.2
+coverage==4.5.3
 docopt==0.6.2
 idna==2.8
-more-itertools==6.0.0
+more-itertools==7.0.0
 pathlib==1.0.1
 pathtools==0.1.2
 pip==19.0.3
 pluggy==0.9.0
 py==1.8.0
 pycodestyle==2.5.0
-pytest==4.3.0
+pytest==4.4.0
 pytest-cov==2.6.1
 pytest-watch==4.2.0
 pyyaml>=4.2b1