Fix dependency install in CI

.gitlab-ci.yml

@@ -2,11 +2,11 @@
 doctest:
   image: python:3.7
   script:
-    - pip install -r requirements.py
+    - pip install -r requirements.txt
     - python -m doctest nnfwtbn/*.py
 
 unittest:
   image: python:3.7
   script:
-    - pip install -r requirements.py
+    - pip install -r requirements.txt
     - python setup.py test