Use poetry to manage package

.travis.yml

@@ -1,13 +1,13 @@
 language: python
 python:
-  - "3.5"
   - "3.6"
   - "3.7"
   - "3.8"
   - "nightly"
 install:
-  - pip install -r requirements.txt
-  - python setup.py install
+  - pip install poetry
+  - poetry install
+  - poetry build
 script:
   - ./test.sh
   - coveralls

README.md

@@ -183,10 +183,8 @@ save_item(dict(name='Alice'))
 ```bash
 git clone https://github.com/ndaidong/bellapy.git
 cd bellapy
-python3 -m venv venv
-source venv/bin/activate
-(venv) pip install -r requirements.txt
-(venv) ./test.sh
+poetry install
+./test.sh
 ```