Update to python 3.8 in gitlab ci

.gitlab-ci.yml

@@ -13,10 +13,10 @@ stages:
 
 python_unit_test:
   extends: .base_rules
-  image: public.ecr.aws/bitnami/python:3.6
+  image: public.ecr.aws/bitnami/python:3.8
   stage: test
   script:
-    - virtualenv --python=python3.6 env
+    - virtualenv --python=python3.8 env
     - env/bin/pip install -r wdfn-server/requirements.txt -r wdfn-server/requirements-dev.txt
     - env/bin/coverage run --omit=wdfn-server/waterdata/tests/*.py,env/* -m pytest wdfn-server/waterdata
     - env/bin/coverage xml -o python_coverage.xml
@@ -36,10 +36,10 @@ python_unit_test:
 
 python_lint:
   extends: .base_rules
-  image: public.ecr.aws/bitnami/python:3.6
+  image: public.ecr.aws/bitnami/python:3.8
   stage: test
   script:
-    - virtualenv --python=python3.6 env
+    - virtualenv --python=python3.8 env
     - env/bin/pip install -r wdfn-server/requirements.txt -r wdfn-server/requirements-dev.txt
     - cd wdfn-server && ../env/bin/prospector
   rules: