gitlab ci caching

+ add pip caching
+ add venv caching

.gitlab-ci.yml

@@ -1,10 +1,23 @@
 image: "python:3.7"
 
+variables:
+  # force pip cache dir
+  PIP_CACHE_DIR: "$CI_PROJECT_DIR/.cache/pip"
+
+cache:
+  paths:
+    # utilize pip caching
+    - .cache/pip
+    # cache the virtualenv to reduce load
+    - venv/
+
 # setup environemnt
 before_script:
   - python --version
+  - pip install virtualenv
+  - virtualenv venv
+  - source venv/bin/activate
   - pip install -r requirements.txt
-  - pip install flake8
 
 stages:
   - syntax
@@ -12,6 +25,8 @@ stages:
 
 syntax:
   stage: syntax
+  before_script:
+    - pip install flake8
   script:
     # breaking errors ie syntax errors
     - flake8 --select=E9,F63,F7,F82 --show-source