fix run unit-tests

Author: Alexander Pazdnikov

.travis.yml

@@ -6,7 +6,7 @@ branches:
   - develop
 
 install:
-  - pip install pytest coverage codacy-coverage
+  - pip install -r requirements-ci.txt
 
 script:
   - set -e

requirements-ci.txt

@@ -1,8 +1,5 @@
 -r requirements.txt
-coverage==4.5
-codacy-coverage==1.3.11
-flake8==3.7.9
-pytest<=4.6.9; python_version < '3.5'
-pytest>=5.2; python_version >= '3.5'
-pytest-flask<1.0.0; python_version < '3.5'
-pytest-flask>=1.0.0; python_version >= '3.5'
+coverage>=4.5
+codacy-coverage>=1.3.11
+flake8>=3.7.9
+pytest>=5.2