Scheduled monthly dependency update for April (#91)

* Update astropy from 3.1.1 to 3.1.2

* Update matplotlib from 3.0.2 to 3.0.3

* Update numpy from 1.15.4 to 1.16.2

* Update scipy from 1.2.0 to 1.2.1

* Update hypothesis from 3.85.2 to 4.14.2

* Update pre-commit from 1.13.0 to 1.15.0

* Update pytest from 4.0.2 to 4.4.0

* Update pytest-cov from 2.6.0 to 2.6.1

* Update requirements_dev.txt

requirements.txt

@@ -1,5 +1,5 @@
-astropy==3.1.1
-matplotlib==3.0.2
-numpy==1.15.4
+astropy==3.1.2
+matplotlib==3.0.3
+numpy==1.16.2
 pyastronomy==0.13.0
-scipy==1.2.0
+scipy==1.2.1

requirements_dev.txt

@@ -1,7 +1,8 @@
 codacy-coverage==1.3.11
 codeclimate-test-reporter==0.2.3
-hypothesis==3.85.2
-pre-commit==1.13.0
-pytest==4.0.2
-pytest-cov==2.6.0
+hypothesis==4.14.2
+pre-commit==1.15.0
+pytest==4.4.0
+pytest-cov==2.6.1
 python-coveralls==2.9.1
+pytest-remotedata>=0.3.1